I think in some ICOs, they give participants big bonuses because there is no any other feature which attracts investors. Such ICOs with big bonuses fail.
For those ICO offering bonuses is not a bad idea at all. This a marketing strategy to attract more investors in their ICO project. Maybe an investors should make some research before investing their hard earned money.
Too many pre-ICP/ICO projects now. This is a lot of work for reading whitepaper.
Many of them hide the hash algorithm & volume in the post. They are wasting your time that they even don't want you to know any technical indicators of coins.