Maybe there's a simpler explanation: FOSS projects can easily turn into unpaid work, and devs tend to burn out.
Projects that start as fun programming exercises eventually take on all the aspects of a full-time job with "customer" support, project planning, maintenance, bug fixing, and so on.
It can become very draining, and if the project isn't unusually popular or high profile and/or there's no other dev support and/or the team isn't solid and mutually supportive it can be understandably difficult to stay motivated.
One of the insidious things about FOSS is the way that devs can make themselves feel as if they ought to be doing all of these things, sometimes in addition to a full-time job.
The problem isn't that they're not up to the task, it's that the expectation isn't very realistic.
Then don't do it. If no one is paying you, you owe no one anything. You have no obligation. Walk away. Our society and economy have lots and lots of money. If the way system works can't justify paying you for your work, then you should not be doing that work. At least that's the way I see it. At this point FOSS is big business, if you are not getting paid, then you should not be bothering with it.
Get someone with money to pay you for it or don't do it. The end.
Projects that start as fun programming exercises eventually take on all the aspects of a full-time job with "customer" support, project planning, maintenance, bug fixing, and so on.
It can become very draining, and if the project isn't unusually popular or high profile and/or there's no other dev support and/or the team isn't solid and mutually supportive it can be understandably difficult to stay motivated.
One of the insidious things about FOSS is the way that devs can make themselves feel as if they ought to be doing all of these things, sometimes in addition to a full-time job.
The problem isn't that they're not up to the task, it's that the expectation isn't very realistic.