Put yourself in the shoes of a senior Russian official in charge of spending that money. There's no way for him to get caught. If his superiors ever find out that he 'misplaced' the funding needed to keep their nuclear weapons ready for action, tracking him down will be the least of their concerns.
There's multiple different types of nukes in Russia. So again it's dangerous to assume every part of their large organization is corrupt. Especially given how important this stuff is.
There's also multiple things that all have to function for a nuke to function. I don't want to under-state how bad even a 10% chance of these working is, but I think there's a only a 10% chance of any given nuke reaching its target and exploding as intended. Some of that's correlated and applies to all the nukes, some of it isn't.
Just for the sake of examples as I don't have any real insight, consider a tritium-boosted weapon that's expected to have a yield of 1MT. If this is set to detonate at the altitude that maximises the area of destruction, but the tritium was last replaced in 1990 and has been slowly decaying without replacement since then, then it's a nasty fireball in the sky that you can sit directly underneath with minimal risk.*
Part of the reason the Soviets went for ever-bigger nukes was that they couldn't aim very well (also a reason for the US to briefly attempt air-to-air nukes, which is how I know you can hang around under an exploding fission bomb without ill effect). If the avionics are all filled with some combination of Soviet-era vacuum tubes but the vacuum leaked, and/or old-and-leaky electrolytic capacitors that no longer hold charge, they won't even reach any specific target.
US anti-missile defence has been improving over the years. I wouldn't want to hubristically claim they're now "good" (I mean, look at the US space industry outside SpaceX), but the defences are likely to be better than they were when the USSR was still a peer.
Someone might have decided it was much cheaper to get fuel for a nuclear a nuclear reactor by replacing a bomb's core with the same volume of depleted uranium.
And of course, if they are ordered to fire, the submarines might accidentally sink themselves instead, like the Kursk did.
* My best guess is that an unboosted primary is about 15kt, but this is still true for somewhat larger primaries as https://nuclearsecrecy.com/nukemap/ says a 1MT nuke maximising 5psi overpressure damage area would be at 3120 m altitude. I assume that if I were in-the-know for exactly what yield was in the un-boosted primary, I'd be under some obligation of secrecy.
