I would add the lack of legal knowledge to the list. In my case I have an idea as well as the energy to implement it, but then questions arise: What about the l

I would add the lack of legal knowledge to the list. In my case I have an idea as well as the energy to implement it, but then questions arise: What about the legal part? What do I have to take care of legally in order to implement this? What about the responsibility in the case of an online service? (If you take for example the case of craiglist, you find something you want to buy and buy it, then you realize it doesn't work, how do you avoid the person who bought the object to not take legal action against you since you are not responsible for this?). If someone else is already doing it in a different way, does this bring more legal problems? If I have no fund at the beginning, can I implement my idea and give away the services I developed for free for a while in order to bring users and then make them pay? Where to get the answers to those questions? If I find some answers to those questions, are they the same in every States?