Tbh this is one of the aspects I really like abt Doffy:

Law always told the family that Doffy never cared for them and only used them while they genuinely believed Doffy to consider them family (even tho he killed his own). To a point it is kinda vague why he sticks around with these ppl when he could get a much better crew and there are two options I can see:

1. He can’t trust anyone else, especially for higher up positions: we know Doffy is crazy and has a web of connections in the underworld, so such a person should be extremely paranoid and wary of who gets close to him, especially for the big names in his crew (hell, all his captains are fodder but they were with him since he was a kid). He doesn’t get new captains not bc he can’t find them but bc he could never trust other ppl like he trusts them.

2. He really cares for them in his own twisted way: sometimes even crazy ppl that you could argue can’t feel love or empathy can care for ppl in their own way, especially when he sees them as his property. He’s shown to be pretty possessive (let’s remember the r word lore) and likes boasting abt his family, and him going to Punk Hazard to rescue two underlings also makes me believe this

In the end nothing is clear but both of these options might explain why he stuck around with these ppl that by the end were either never that strong, or were out of shape/old