1) Because they are not securities. You don´t own any shares of the companies. You don`t get any dividends from their gains in the future (if any of them has the capability to earn FIAT money in the future).
2) ICO ... Initial Coin Offering, it´s just an other form of crowd funding. What´s the main problem with this approach? You finance the companies business operations. They must sell their tokens to sustain running their business. Or do you think they earn money other than in cryptocurrency? No, they don´t. It will last until all tokens are sold, then this companies are down and out. Simple. You sit on worthless tokens. Scams are just the rapid version of this process. Would ever a venture capital company invest FIAT into their business? Zero price is inevitable.
3) Point 1 and 2 are not clear for many users here ... It´s a big pump and dump scheme. Greater fools theory, not more not less.
Now I want to hear your opinions. We don´t talk about Bitcoin here, just about altcoins.