That infinite horizon of possibilities is both a positive and a negative. The negative is that you have highly imperfect information and you never know what the optimal thing is that you should be doing next. I've been a solo product developer for >15 years now I can tell you that feeling of uncertainty never goes away. Although I have solved it to some extent by factoeing in enjoyment. Whenever I have 2 possibilities and I don't have a feel for which one will give the best result, I do the one that is more fun!