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Professional integrity. Have you ever worked for a company that got screwed by a consultancy? Vendor lock in and charging scandalous amounts for little offer.
You are paid for your skills and your time. If you're confident in your ability and impact, you shouldn't have to be worried.
I'm not saying sacrifice for yourself for your company, and if they are a shitty company that would replace you with cheaper, get out, but also, giving nothing for the pay you get is a bit dishonest, and then you are no better than them.
Plus, you make the case that hiring people is bad and paying a consultancy is less risky.
I wouldn't recommend staying with a company for 17 years. That's for sure. Best way to get stuck in a company specific niche skill that is not transferable. For the reasons stated you got to keep yourself positioned well skills wise and relevant so you can jump into any role you need at any time.
Integrity is not for the company. It's doing things the way you think they should be done and earn your own respect.
I would say all companies don't replace with cheaper. Many do. Especially the shitty ones. It's quite easy to avoid those like the plague. Many did, and learnt the hard way, many have staff that have seen failed outsourcing and are in a position to influence that.
Soloing knowledge doesn't keep you safe though as the penny pinching companies will remove anyway and clean up later regardless. It does not keep you safe. It's a false sense of security. Complacency is a death sentence in software development.