There's a huge reason to avoid betting on unpopular sports.
Usually the teams are not close to a fully professional level which means that their form isn't predictable or reliable. Therefore the odds are really shit.
Unless you have good knowledge of these athletes yourself for some reason, it's not worth the risk.
For instance, if you bet on handball, most athletes in most countries have to have second jobs to sustain their presence in the sport, sometimes even in the top teams on this sport the salary isn't enough. What does this mean? Very few athletes that would otherwise be peak athletes are willing to partake in the sport after a certain point. Each team's performance is therefore hindered by many issues. The same teams playing against each other in a different universe can deliver wildly different results. The small teams can beat the huge ones etc.
And yet, the NCAA, the biggest college league for several sports, makes millions from broadcasting these games, selling rights and sports betting results.
But you would notice that in NCAA, even if you bet on a parlay with 10 games of 1.05 odds, it's more likely you'll be losing because upsets are more common than in a fully professional league.
Athletes in college sports are putting all this effort and are paid nothing. Did you know that until very recently when there was a huge lawsuit reaching judgment, there was no agreement to compensate college athletes at all in the US?
https://www.thedp.com/article/2024/10/penn-ncaa-settlement-player-paymentSo this also brings us to the point where ethicality has to be discussed. If we're spending money betting on a sport, doesn't it feel a little wrong to know the athletes earn nothing or close to nothing from this activity? Maybe at least crypto bookies should take the initiative to fund more small sports associations on the local level.