A game made by one person appears in the news, sells well, and becomes a story about what determination can achieve. Several hundred other games by people in the same position did not ship, and those do not get articles.
That is normal survivorship bias, but it matters because the success stories are used as evidence that small teams can reliably do this, which is not what the data supports.
What a solo developer is actually solving
The programming is rarely the hard part. A competent developer can build a working game with real systems on a small budget, and the technical risk is manageable.
The hard parts are the ones that take years rather than months. Content volume is the big one: a commercial game needs enough levels, art, and variation to justify a price, and each one is a separate piece of work. Then there is playtesting, which requires other people, and marketing, which requires a sustained presence over the period before release.
Why the successful ones succeed
The projects that ship tend to share some things. They are small in scope relative to the genre's norm. They had an unusually strong public following before release, which is years of content creation that happened before anyone called it a project. And they had a funding runway, whether from a publisher, a grant, or savings, that covered the period before revenue.
None of those are about skill. They are about resources and timing, and they are the parts that cannot be read off a success story.
What that means if you are considering it
Scope is the variable you control, and it is the one that decides whether the project finishes. The projects that ship cut scope repeatedly and early, accepting a smaller game in exchange for existing. The ones that do not ship usually held out for a larger vision past the point where cutting was still affordable.
If you are evaluating whether to back a small team project, the questions are about runway and completed work rather than vision. How much of the game currently exists, in a playable form, and how long the funding lasts. Both are answerable, and both predict outcomes better than the trailer.