(This may identify who I am to someone who was paying attention on BoS or other places around that time. If you know who I am IRL from this post, please kindly STFU. )
At the time I was attempting to offer a service to mISVs that would have had a very good ROI. I did land a few successful projects. Not many.
Generally, the ASPers and the BoSers were a bunch of assholes. Scoffing at anything I said when I approached them one on one.
I infer from that experience that the vast majority of them had very poor revenue and were unstable. There was an angry edge from most of my contacts with those people.
It's something you see in the grocery (for instance) when shoppers are pissed because they can't afford a lot of stuff they want.
I think the mISV niche was always pretty marginal with sporadic successes, and went downhill very quickly. The disappearance of JoS and BoS no doubt removed a lot of what little momentum remained. I think the closing of the ASP (similar experience going to one of their conferences) also indicates that mISVs are a tough business.
I disliked ASP when I joined ASP briefly. The members were in the hostile curmudgeon end of the spectrum. I had a negative experience with those losers in the early 90s. I downloaded a shareware library of some kind (forgot it, really) written by an ASP member. I mailed the guy a check to get an unlock code and the rest of the library. The fucking check never got cashed and I wound up putting a stop payment on it. The "ASP ombuds" I spoke with was a totally useless fence sitter.
FSK, in my opinion you should consider just about anything else for a side hustle or retirement gig. IMO the niche made anyone who tried it kind of bitter.