So helps me understand your point of view, but to me many of the examples are a bit odd.
The first set of stuff circa 1900 was about how much (or little) to pay crew, not about whether to pay them. I doubt it crossed the minds of the gentlemen owners of Royal Thames that they might ask one of their friends to do the work of 'the men'. I'm also fascinatined by what 'losing money' was and how and why it was paid. so would love to know what was elided by the ellipsis in that example.
The seahorse example from the '80's implies that the attendance at major regattas diminished when the ORC tried to limit pros because the classes with no pros attending were considered less prestigious, or am I reading that wrong?
RTYC ran a series of races for amateur crews as early as 1884, and they were well after the first clubs and events just for amateurs, so your doubts about the sailors of the time are baseless. However, it was recognised that in general, pros were more likely to win, just as now.
The whole issue of "corinthianism" or "amateurism" in sport at the time is a big field to study. It's significant that sailing had its boomtime in the post WW2 era when even America's Cup crews were largely amateur because of the success of the "Corinthian" ideal.
To get into the question of "losing money", winning bonuses, messing allowances and all the other intricacies of paying crew is complicated and you are welcome to research it yourself. Winning bonuses are obvious; some owners also paid money when their crews raced (as distinct from cruising or sitting on the mooring) but lost.
The basic point is that since the 1800s, it has been recognised that paying for pro crew could drive owners out of the sport.
I can't recall whether Seahorse said that the number of boats in level rating regattas reduced when pros were limited. The main point was that they were saying that the increase in costs due to the rise of pros was a major factor in the huge drop in level rating racing at that time.
The idea that increasing the dramatically increasing the cost of being competitive in a sporting competition will generally reduce participation is so obvious to most people that it's odd that some people reverse the onus of evidence when it's discussed.
Carping about the examples I gave is very odd when I clearly said I was away from my sources, and when your side has given no evidence at all but apocryphal tales that can be rebutted by equally experienced owners and sailors.