A cryptocurrency is basically a distributed database, except that you are getting different actors who don't necessarily trust one to run it cooperatively.
All these people harping on about: "Bro I just need to move my money without trusting anyone!, I just need a trust-less way to send currency bro!"
Trust is a good thing! Banks and financial middlemen aren't the devil. Look at how many TPS the visa network can do thanks to trust.
If it weren't for some minimum of social/institutional trust the whole of society would collapse anyway and your digital coins would finally converge to their true value (zero - or actually negative once you add in the externalities).
(but also, as OP, Stripe will almost certainly not have any use for this)
Etherium itself is not a computer, that's marketing speak.
In other words, I can unilaterally and without permission deploy code to the Ethereum chain, at the price of "writing the code" and "paying the Ethereum fees to do so." And when I do that, the ENTIRE CHAIN must follow.
That's closer to "a computer" that just "a listing of optional scripts."
To host validator node you stake ETH which is serve as collateral in case your node misbehave, go offline, etc.
If specific validator cheats at any point and end up approving bogus data he'll be punished by loss of staked ETH and penalty grows with each attempt to cheat. If multiple validators commit the same bogus data they'll get even more severe punishment for coordinated attack on chain.
It doesn't take a supercomputer to host ETH node so there is absolutely no incentive to cheat unless you actual bad actor who is attempting 51% attack. And to perform said 50% attack you will need like $75-100B+ of ETH stacked since currently there is $150B of ETH stacked for Proof of Stake. So this kind of attack really doesn't make any financial sense.