First off I don’t think anybody that we know did steroids before the vote came up has been voted in. McGwire was the first eligible after things blew up and he’s still out and the voting looks like he’s going to stay out for a long time (he’s not even pulling 25%, and I think you either need 2/3 or 3/4s to get in). I think a couple of guys are in that we found out about later, but nobody that we’ve found out about before they became eligible has been voted in.
Secondly it’s good to keep in mind that for most of the steroid era they weren’t actually against the rules (the MLBPA stood very strong against it during CBA negotiations), and even when they finally became against the rules there was a couple of years there when there was no testing (good old PA again).
And finally, yes gambling is worse that roids. At least the guys on roids are trying to win, and trying all out. With gamblers we just don’t know. Again look at the litany of lies Rose has put out for the last 20 years.
Rose bet on how well the team did, perhaps he bet on how well he did, but I don't recall hearing that he ever bet against his team or himself.
McGuire, Sosa, Bonds etc were using steroids to improve their performance, set the personal records. Other major leaguers used steroids just to stay in baseball. A me-me thing.
Last time I checked baseball is still a team sport.