I wish I had more experience, because then I could help you more. I unfortunately am in a similar situation and have less work experience than you do. My sources will mostly be from my studies and HN. I hope some people will amend my thoughts or challenge them strongly.
Some hopefully helpful thoughts:
1) Is it for fun or profit? You can't have both motivations
One thing you should think about with #2 is the overjustification effect [1]. I think there's a cognitive dissonance effect at play [2]. In practical terms, ask yourself: are you having a side project because you like to do it, or because you want to make money and "scratching your own itch" is simply a marketing tactic of understanding your users? If you say: well, both! Then you're prone to the overjustification effect and you might sap a lot of intrinsic motivation away.
2) Generalists tend to earn less money
There was a recent thread on HN that made me believe that specialists will fare better in big(ger) companies and generalists will fare better in small ones. Since big(ger) companies tend to have more resources, specialists tend to be paid better salaries. I presume your entrepreneurial motivation is in part financial. Being an entrepreneur prepares you to be a generalist [3].
3) With that said more motivated people are more competitive and earn more
This is a bit of a tricky one. It has been my observation that CS students who enrolled into university and were passioned about coding tended to be more competitive on the job market than the average CS student (if I have to believe my LinkedIn, which has +500 connections and +100 recent graduated programmers on it).
One confounding factor, however, with competition is not that you simply have to be motivated. There is a certain baseline of motivation depending on whom your competition is. For example, the gaming industry is a more competitive industry simply because employees are more motivated (I read it somewhere, I do not have the source). Another confounding factor is that the distribution of wealth regarding an industry matters. If you are the 50th percentile earner in the compiler industry, you'll earn a lot more than if you are the 50th percentile earner in the game development industry (with its many indie companies that are underfunded).
What I described here I'd equate as (with the strong assumption that people their ability to learn is similar and they are at a similar level as you):
wealth = motivation_percentile * wealth_distribution_percentile
motivation_percentile: your motivation ranked to that of peers who are in the same industry. A simple metric is: amount of hours worked on relatively high focus.
This is a long way of saying: do you know how motivated you are compared to your competition? And do you know the wealth distribution of what job and/or app you're getting into? In terms of entrepreneurship on wealth distribution: education is less lucrative than healthcare, for example. A heuristic following from this: if you can find a boring industry that you're excited by, then your chances of success are higher.
4) How many product market fits are you able to validate?
It took Rovio games 52 games in order to produce Angry Birds [4]. I am not sure if this is a fair comparison as many industries are different and the average amount of tries to make it big can vary. However, based on stories of most entrepreneurs, I think it is safe to assume that this number tends to be bigger than 10. I hope other people could get some good statistics on this, I couldn't find any.
[1] https://en.wikipedia.org/wiki/Overjustification_effect
[2] https://youtu.be/h6HLDV0T5Q8?t=488
[3] https://news.ycombinator.com/item?id=20094242
[4] https://en.wikipedia.org/wiki/Rovio_Entertainment#cite_note-...