I don't believe anything anywhere in crypto can ever be considered investing. It's all degrees of speculation.
As far as I can tell your only hope with an ICO is selling your token for more than you paid for it to someone else who intends to do the same. There's no other type of return and never will be. That don't smell sustainable to me.
It could have been investing if at least some projects succeeded and fulfilled their promises of their tokens generating profit, but I've never heard about it happening. I've tried to do some research on succesful ICO's, and all I've got was stories like "this ICO have gathered millions one year ago and it hasn't officially failed yet". I don't think even Ethereum can be considered successful, it has increased in value by some giant amount since its ICO, but it still lacks in functionality and no one is seriously using smart contracts. If it will continue to be like this, it will just die in the long run.