Some investors are ready to invest on any project they come across just because they really want to make profit and some of this projects are considered to be a scam project which people invest reasonable amount of money. It is very painful when money is invested in this project and they end up becoming a failed one. I think good reasoning before investing will really help investors from losing much money about projects they do not know about much. Investors needs to ask themselves before investing "what if I lose my money investing it in this project? I think this question can help people to invest with the amount they can afford to lose or not to invest at all on project very not sure about.
Investing without any reasoning can just make one to invest without considering the risk and the probability of making lose or making gain from the investment.
When it's about large sum of money you should do extensive research. I've in past experienced loss when my research were superficial. Sometimes the project seem too promising but turned out a cheap copy of something else that don't have the capacity of developing the network as promised and sometimes I bought a good coin but at wrong time. i.e. when it was at its peak. So, by research, you need to have a detailed look about what the progress had been made, how are the price changes from start. Even coinmarketcap chart can be confusing as they make it after they list it while the coin might have been trading for a while.