Is inflation really needed? Really?

I was just thinking about NEO and how they have a fixed supply of 50m tokens and thought how stupid that is of them because they will get incentive problems to attract validators to produce blocks.

I tried to imagine a scenario where NEO would get in big trouble because of that but after some time I still had no real scenario where this could go horribly wrong.

In a scenario where transaction fees would be the only income for validators there would be a huge incentive to increase scaling. There wouldn't be "spam" only times in which it really pays off to stake. Validators would be holders that want to increase the value of their tokens.

Even if there would be times where noone would transact and thereby validators would generate no income, do you really think the chain would just die off? This would destroy the value of the token, and token holders wouldn't let this happen.

Wouldn't 100mio ETH ever and never more be a beautiful number?

If other people view ether as a store of value this also increases the number of potential users (and thereby utility of the ethereum network) as these people would like to use the system for which using it increases the value of their holdings.