A whole lot of speculation going on around your part. Especially when we've never seen a bounty of 1 billion from anybody that is not a first mate regardless of how much of a maniac you think they are (suicidal is just Kaidou).
Before the introduction of all the other yonkou, bobbin tore down a whole country just because they didn't have candy. Do you not believe that it's sadistic enough such as Jack who tortured the minks for them to control the wano country by finding Momo w/co. ?
At least Jack gave them a chance unlike Bobbin and bobbin isn't even a commander.
So to assume that
Its not speculation, its called context and using common sense to see things in between the lines. They're name literally says it all, they're the beast pirates. Its clear even this early on what Oda is trying to let us, the readers, know about them.
Kaido isn't the only suicidal maniac in the crew clearly, what person in their right mind tries to fight Sengoku, Fujitora, and Tsuru all on their own? There's no way in hell Jack thought he was just going to get out of that unscathed, what do you think was going through Jacks head when he did that? Nothing, that's what, because Jack and most likely the other crewmembers don't think, they just act, they're animals. You think any of BMs crewmembers would do something like that?
Yeah I get that but we have no idea how Bobbins destroyed that island. Knowing his abilities he could have put the people there to sleep and then destroyed it, leaving no clues for the WG to know it was any BM pirate.The beast pirates imo, are being built up to be a crew just as wild as their captain, it would also fit their theme sense they are a bunch of zoans.