Slop aside, do you think it's reasonable to assume a decent fraction of those making consistent profits are arbitrage bots?

arbitrage is a rather overloaded word that people use for all kinds of strategies but yes, I predict most of the most profitable and consistent accounts are not actually attempting to forecast the outcome of these markets from first principles

That sounds plausible. Not a trader so I wouldn't know. Saying at least a little about what's actually wrong with it seems more useful than just saying it's slop, which gives me very little info over just a downvote.

it's pretty easy to write basic trading api connectivity. the hard part is knowing what trades to send

even if we are very charitable and assume the comment refers only to like high-engineering-effort infra for trying to be super competitive on latency, that's still like the opposite of a durable edge, since everybody is looking at it. there's very little "hidden" knowledge and it's mostly a matter of elbow grease and careful engineering.