user incompetency

For sure, it's an uphill battle against never ending stupidity, but that's not exclusive to crypto haha. I'm sure we'll get there sooner or later though

I doubt the growth would be that small if it had actual use

You'd be surprised.

Bitcoin's chain size is "only" 500GB because it's pretty much enforced by the block size limit (which is 2MB). The amount of use does not affect the growth (unless it's below the 2MB, which it hasn't been for a whiiile).

For Ethereum, the "fullnode" only requires a bit over a terabyte because only the latest state is stored (combined with all historical transactions). If you wanted to query old state, you'd need an archive node which holds the state of each block that's ever happened. Archive nodes are up to 10TB afaik at this point, which is a good chunk of data if you ask me ;)

The nice thing is though that you can build an archive node out of a fullnode, by replaying all the transactions that make the history of the whole chain.

You also have to keep in mind that every storage operation is very expensive to do (precisely to prevent huge increases in chain size), which means that people will spend a huuge amount of time optimizing their applications to use the least amount of space possible (thus reducing cost for their users). So that's probably why the chain size might seem "small" to you.

There are chains though which do not enforce such strict limits on space usage, like Solana, which is apparently at over 100TB now.