Any investment should be analyzed objectively and thoroughly. If you research a potential investment with care and are not emotionally attached to the investment, your decision as to whether or not to invest should be solid and well supported. As such, if by chance many other people are investing in the same investment, so be it. However, you should not invest in something solely because you know others that are doing so.
That being said, some other people may have more expertise, knowledge, and/or experience in a certain area of investment. Therefore, if you notice one or more of these people jumping into an investment, you may want to inquire as to why they are investing. It never hurts to ask and you would be surprised how many people would be willing to give you information. However, again, you should be cautious about making your decision because even well educated and experienced people have made financial mistakes. As such, it always behooves you to do your own analysis before deciding to invest.
It can be very tempting to jump into an investment without first researching the same. As such, you may be willing to throw your money into the investment blindly without conducting research. The best case scenario is that you get lucky and actually make some money. The worst case scenario is that you lose everything. However, even in the worst case scenario you do get something out of the experience. At the very least, you learn that you should never jump into an investment without first doing your own research. Granted, this is a powerful lesson to learn but you never want to learn it at the cost of losing your entire investment.
Following in the footsteps of a financial mentor or listening to the advice of a financial expert are additional things that you can do in order to bolster your investment knowledge. Doing these things will also provide you with tools and outlets that you can utilize for the purpose of discussing and getting opinions on a potential investment.
Whatever you decide to do, make sure that your decision to pursue a particular investment is not based solely upon the actions of others. These actions may give you a clue as to a potential good investment, but always do your own research because ultimately, you are investing your own money.