Every breeder has to start somewhere, and every breeder necessarily starts with genetics worked by others. That's how all breeding of EVERYTHING is done.
I think there is more than one way you can get into the breeding game. It depends a little bit on what you are trying to accomplish.
Are you trying to create strains you like, strains that fit a particular need, trying to make money, or all these things?
If you just want to make cash selling beans, the easiest thing to do is become another pollen chucker. See here for the recipe (scroll down to the bottom of the post):
https://www.rollitup.org/seed-strain-reviews/395623-riot-seeds-14.html#post9321072
I'd say the best first step to doing this ethically is to create a few good lines of your own. You can start with other people's genetics, you just need to work them into something unique, good, and (preferably) stable that there is a real market for. Some of that requires knowledge of breeding, but it also requires knowledge of the marketplace. If what you create truly stands out in today's crowded field, and there is a market demand for it, then actually getting the ceeds to market should be relatively easy. If you can create 3-4 lines that people actually want to buy, then bang, you're a "breeder" of note, but you only really need ONE good line to get started.
Yes. . .that's real work, which is why so few people do it.
I'll give an example of one new breeder that I'm aware of, Red from Sickmeds. He has created several novel lines of his own design (eg "Bizarre", "Chupacabras", etc), but his two most famous/best selling ones are Green Crack S1 and Williams Wonder. . .neither one of which required conventional breeding to get to market.
Green Crack S1 he did basically as a "community service" because he felt there was an unmet demand for ceeds of that line, (especially in Europe where clones of it are exceptionally tough to get). Red got some clones from two different sources in Europe, grew them both out to ensure they were the real deal, selfed them to make ceeds, tested them himself to make sure the S1s were reasonable, gave away some to testers (you can see one test report in my signature below), then charged a reasonable price for these. Bam. . .instant demand.
Williams Wonder was (/is) a legendary pure indica that hadn't been commercially available in ceed form in maybe 20 years of which there was good pent up demand. Red had to do quite a bit of wheeling/dealing to get his hands on real-deal SSSC Williams Wonder beans from the late 1980s, and then he had to get some to germinate, grow them out, do what selection he could (not easy when you're dealing with barely viable ceeds) and effectively bring the line back. Again, self testing, outside testing, put on the market. . .and the line is now so popular its actually hard to get ceeds.
This wasn't so much a "breeding" project as a "restoration" one, but IMO he put himself on the map with it, and bluntly it was more of a real accomplishment to bring this line back from commercial extinction than a whole bunch of pollen chuckers making noises about F1s they've created from other people's clone only lines. Not incidentally, although older, the line itself is probably still better than 90% of the pollen chucks anyway.
I don't really know of many/any "William's Wonders" that are left out there to be brought back, but I can think of at least a few genetic market niches that could be filled right now. For example, there is a lot of demand for quality autoflowers, but most of the auto lines aren't that good. Anyone who can come up with one that has great flavor and potency could have an instant hit. Specialized cannabinoid ratio autos is another niche that I don't think anyone has opened up yet. Etc.
