That is the issue, yes you can make a lot more money with icos and with cheap altcoins but the risk the coins go to zero is quite high, more than 90% of the blockchain projects fail in less than a year, ETH may be down right now and the same is true for any major coin but the chances it goes to zero is very low compared to a new project that is why the risk is lesser than with the other altcoins.
the risk of ETH going to zero is much greater than some small altcoin going to zero. times have changed and now any small project will usually get thrown millions of dollar at. this was different a year, two years ago when they were all struggeling.
so now its a very small chance for a small project to go to zero just because they have so much money. why should they leave, scam people or quit? where else can they make so much money?
having vitalik butin be worth $100bn is the insane stuff here, many smaller devs still arent worth $1m... you realize the difference? of course not everyone will deliver something great but same can be said about vitalik, now he seems to mostly give his money away instead of working hard.
Vitalik is not really doing anything special. he stole the idea which was already around and built something around it which is full of issues. you know he was pushing to build it on bitcoin but thankfully he was shut down. and the only reason he is worth whatever billion dollar is because he premined the shit out of ethereum!
i fear for the future of it though. it is hyped up and it seems to have little chance of going down (despite what you said) but it has lots of issues as i said and with things like Rootstock (which is practically going to do what ethereum does but for free and on top of bitcoin) it will lose its place!