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.