The biggest mistakes developers make that leads to bad ending for many projects are
1. Huge Discounts
Many new projects are still making this mistake over and over again, huge discounts like 50% is insane and it always bother me how the hell the early buyers won't end up dumping since they have already see big profits.
2. Lack Of Solid Products and Ideas
Lack of working products and real use cases is why many investors are not taking new projects very seriously, no one would want to hold such tokens or coins for long, developers need to start working on how their project's token or coin will be very demanding throughout the globe
3. Bad Exchanges
Imagine new projects that make over millions of dollars in ico or ieo and end up listing on bad exchanges with no enough volume, what do they expect to happen?
1) Such huge discounts for first investors indicate that developers are primarily interested in quick fundraising, rather than stable development of the project.
2) Here you are right, the project should be of real benefit to society and its coins should be easily applicable in real life.
3) This is also a huge minus for the founders of a cryptocurrency startup. Actual and potential investors may become disillusioned with the project, which has a bright roadmap, but his coins start trading on a low-liquidity unknown exchange.