I have no reason to doubt your talent, but I have an aversion to the "I could do it myself" argument. What does that even mean? You could do it yourself if you had a year to work on it? 10 years? A lot of software contains code icebergs which render this "I could create this myself in a [insert short time period]" thinking moot.
Yes, doing it yourself in a short time frame is not realistic in most cases. The real 'problem' are those people who make free software as a hobby. They write these softwares for years (sometimes with more free time than I would have if I would decide not to sleep at night at all), and this raises the barrier to entry for those who want to create paid products (for example bootstrapping on the side, with a family to support).
You should be able to differentiate yourself from those projects by focusing on something full-time and adding your unique expertise to the mix. You are a unique human being, after all. If you can't, you shouldn't bother.
I created Stormpulse while bootstrapping on the side with a family to support. Ultimately the competition became irrelevant because it's an extension/expression of myself which can't be easily duplicated and provides immediate differentiation.
While more products in a market does make it less likely that a new competitor will gain share, the fact that free tools exist to do almost any coding-related activity so significantly lowers barriers to entry that it seems very likely that the net effect of open source is lower barriers overall.
In any case, I'm not sure that the existence of competitors can be considered a barrier to entry.
I didn't intend to brag, because I'm not a particularly good programmer. I only mean that, once you've taken the "Compilers" and "Operating Systems" classes in college, there's really no mystery left.
You are absolutely correct that it would take me a long time to do any of it. (I'm also bad at estimating how long things take, BTW!)
Then again, for most big polished software I use, I don't use most of its features ever. There may be icebergs, but chances are most of them are in code that I wouldn't write in the first place, if I was only writing for myself.