And the tokens they are buying is just a promise - they don't bind the company to do any thing. The company promises to use the BAT token in their future monetization model - but in fact they can pivot at any point, like many (if not most) startup do, and do something else, or maybe even do yet another ICO with another token. And that is on top of all the problems with crowdfunding - where even if there is a legal binding, and maybe a fractionary ownership - without all the regulations that were invented to protect the investors - the founders/executives still can do anything with the money they received from the funding event: https://medium.com/@zby/the-problem-with-crowdfunding-81b53f...
Update: Even if now most ICO creators are honest - then soon they'll be crowded out by scammers, because honest funders will find other ways to fund their starups - but for scammers it will never be easier than with ICOs.