What insults?

Fact of the matter is that humans are getting too old.

What is your definition of "too old"?

The majority of people past 80 are not healthy anymore.

It would be good to have some numbers on this. I can't look for some right now.

However, what are your standards for "being healthy"?
Having manageable diseases is not equivalent to being connected to and depending on life support machines.

Neither can or should they be expected to still work a job.

I would make such a decision not generally, but on an individual basis. Incorporating the fitness of everyone seems fair. What are your reasons for why they shouldn't be expected to continue working for a couple of years?

So many personal attacks trying to beit me into "hah gotcha!" moments and strawmen.

Yeah, sure. It's all personal and not regarded to your views and opinions which I find shitty. /s
When do people start to realize that respecting a person is something different than finding their opinions bad?
To make it clear, I still respect you as a person, but I don't agree with some of your views. Even more, I actively find that those really, really suck.
If you felt insulted as a person, that was never my intention. So please clarify where you felt like I insulted you, so I can react to that accordingly.

No I don't want to live past 80 personally. I'd be completely fine with dying at that age.

Alright, no one is stopping you from that. But I'm pretty sure that most people would like to stay alive.
And I find it wrong to deny them this just because it is appears challenging to care for them right now while upkeeping the standards of living in a nation like Germany.

I specifically said we should stop life prolonging treatments at a certain point, not actively kill people or deny them any treatment for not life threatening health concerns.

You specifically said:

What about a fourth option of reducing the amount of old people?

"Reducing the amount of old people" sounds pretty active to me. Denying them treatment which could cure their diseases or upkeep a high quality of life is an active decision. That's deliberate acceptance of suffering and death. Letting someone die, because they got a morbidity after reaching a certain – almost arbitrary – age, may less be an active killing, but it's still negligent homicide.

Also, regarding the treatment of life threatening health issues, a lot of diseases may start harmless and become life threatening when left untreated. Say an infection of a wound for example. May be harmless at first, sometimes the body is able to fight it off by itself, but sometimes it is not and needs support. And then there are diseases which are already present before someone reaches pension age.

Also, aging and death itself can be understood as a disease, which humanity is fighting since even before they were humans.

Where do you draw the line?

There is nothing misanthropic about my views, nor am I making them out of financial concerns

No? Talking about pension and suggesting we should, as you put it, "reduce the amount of old people" has nothing to do with finance?
A few lines later you say in the same paragraph:

Or how older people hoard wealth? The majority of housing and any monetary wealth is in the hands of the older generations

To sum up, "I don't want to let old people die for financial reasons, but I want to let people die for financial reasons".
Contradicting much, doesn't it?

but out of concerns for human society and its prosperity

Besides the matter that, "prosperity" can also be understood as a financial matter, could you please clarify what you mean with "human society and its prosperity" in the context of our discussion? That's so abstract that it could mean anything.

Regarding wealth and housing, referring also to this:

The majority of housing and any monetary wealth is in the hands of the older generations and until they die it will not reach any generations after them.

Due to the fucked up inheritance laws in Germany, society as a whole does not really profit from the death of those old people, because those are bequesting it almost tax free to their descendants. So just a small group of rich people stay rich and get richer. Even if they die and their younger descendants take their place, most people won't profit from that in any way.

Not unless we have an entire social revolution regarding property and wealth.

I'm not sure about the revolution part, but at least we seem to agree on the importance of redistributing wealth somehow. That could also help with the aforementioned inheritance issues.

You're coming from a position where you view it as necessary to keep the population growing or at least at the same size.

Yes. To a certain level I do.

Unless we fall beyond replacement levels for humanity as a whole, that is no real issue.

I'm not talking about humanity as a whole, but about the population in Germany.

It's only problematic for our systems built on permanent growth.

That's the lesser issue here, I'd say. It's currently a problematic topic in Germany, because there are a lot more old people than young people. This will lead to a significant decrease of living standards and probably bring along a bunch of other problems, since few younger people need to support a lot of elderly.

Degrowth itself isn't an issue, it even found more and more advocates over the recent years.

You may also find me on the degrowth side often. But please, by other means than death.
Brith rates worldwide (as a whole, not necessarily individually per country) are declining by the way.

it's a too complex issue for current governments to handle within our current system

There is no societal issue a government can't handle. That's the whole purpose of having a government.

Children are already subsidised a ton by the state in Germany.

And yet there is talk about child poverty since years. It seems what you view as "subsidised a ton" differs a lot from what I, parent associations and a bunch of other instutions criticise. It's something, but sadly not a ton and not enough.

Just subsidising children more will not fix the issue.

Yes. But it will help until the structural problems, the causes for these problems, are fixed.

I basically agree with you concerning the rest of your birthrate paragraph.