Not much to add here, but walk-ons do sometimes, if rarely make it. Had a nephew who was a recruited walk-on at a low ranked midwestern D1 and he was cut. Still at the school cause he loves it. ON the other hand, son's HS teammate was a recruited as a walk-on to a UC, he too was cut. Played club ball for a year and is now at a JC. But on the flip side, my son's travel team teammate was a recruited walked on at Big 10 school, played his tail off in fall ball, absolutely raked during the fall world series, and from what I gather he's likely to be starting. Opened some eyes. So it can happen. Risky proposition, no doubt, though.
On the other hand, at some D3's, including some high academic D3, some very fine baseball is being played. A fella could do a lot worse.