Bots for arbitrage are most definitely not going to land you a profit, but arbitrage in general is a real exploitative strategy of the time/valuation lag in markets.
The problem with buying bots for it are that you run into the likelihood of it being a scam, or the likelihood of the strategy being too saturated by virtue of its being-sold status.
If these bots works as they claim, why would they be selling it rather than using it themselves? It would make more sense for them to just run it and keep it a secret right? Also these bots do promise for profits so I'm not too sure yet.
Actual arbitrage is legit, the bots probably aren't.
A lot of these bots post screenshots of their results, are they faking the screenshots? It seems like an easily automated process if you can figure out the technicalities.