Couple of thoughts, here...
First, as is usual when Neck Dive threads show up (and they show up a
lot), I always find that there's a tendency to conflate "Solve" with "Compensate for". Much as we'd like them to be the same, they really are not. So...
Solve - IME, the only way to solve Neck Dive is to change the balance of the bass as it hangs from your shoulder. And, again IME, there are only two ways to change the balance. 1) Remove weight off the headstock; add weight to the other end; or a combination of the two: or 2) change the location of one or both of the strap attachment points... Sometimes, depending on the bass, you may have to do both. However, if "Solve" doesn't quite do the job - or you're not willing to screw with your bass? Then there's always...
Compensate for - This basically consists of all the strap shenanigans; wide straps; grippy straps; wide
and grippy straps; dual straps; and so on and so on... Changing the angle you play the bass at sometimes falls in here, too... The main point here is that your bass still neck dives; you just aren't letting it. How well this kind of stuff works depends on the bass - and you...
So... what do
I do with a bass that "neck dives"? That depends on the individual bass...
First, I differentiate between 1) basses that really do have neck dive; 2) basses that have what I call "a slight forward bias, weight wise"; and 3) basses that just want to hang at an angle that's playable, but not quite the angle I really prefer. For basses that really do neck dive - and I have a few - moving the strap buttons has worked for a couple of them. For the others, a wide grippy strap compensates for the dive sufficiently well - for most of them. For my '78 Kramer 450B, though, there really is no solution, and nothing can really compensate for it. I just put a wide, slippery strap on it (a grippy one just pulls my shirt up around the back of my neck); hold that heavy aluminum neck up as best I can; and don't play it for more than two songs without a break...

For basses with a slight forward bias - and I have a few of these, too - I sometimes use a grippy strap; sometimes I just hold the neck up. I'm not so old and feeble - yet - that holding up the equivalent of a Big Mac is more than I want to deal with. As for the basses that like a particular playing angle? Most of them like to be almost parallel with the ground (my 2 Ricks, for example); that's close enough to the playing angle I prefer, that it's not really a problem. A grippy strap compensates just fine, if it is. My Thunderbird kinda falls into this category. Any neck dive it might have goes away completely if I play it like most T-Bird players do; slung low, with the headstock way up at about a 50 degree angle. It feels like that's how it's supposed to be played, anyway; so I do. And looking kinda badass is cool, too...
As for the rest of my basses? They hang right where I want them to, and stay there until I take them off...
