Another quirk of this kind of massive inefficient bureaucracy that was briefly touched on earlier in the show is that some facilities (namely the shipyards in that instance) would never admit to a theft if one even occurred for fear of exactly the kind of Imperial crackdown and takeover Preox-Morlana suffered because of Ferrix. Those few still operating under Imperial contract rather than being fully nationalised would rather eat the cost of a robbery than admit one ever took place.
How is this relevant to Aldhani given that it's a military installation? Simple: security arrangements are usually determined by assessments based on precedent. If there's a systemic unwillingness to admit failure and thus communicate inherent weaknesses to the wider organisation, then operational security will be habitually overestimated, while external threats will be habitually underestimated. The result is cluelessly lax security...until something that can't be ignored gets nicked then everyone runs around like headless chickens, which is what we're seeing now.
As for the money; let's keep things in perspective. 80 million may sound a lot, but it's not enough to fully finance the wider rebellion. It's a massive boost to be sure, but it will only go so far.
Yeah, you can buy a ship for around 10-20k. But in Star Wars "buying a ship" is like buying a car. The rebellion doesn't just need any old ships, it need military grade ships. Fighters. Frigates. Fleet tenders. Corvettes. You can bet those go for a LOT more than just 10-20k on the black market. Like if a second-hand civvy R-22 goes for anything less than half a million a-piece, I'd be very surprised. And that's before they could even get into building their own X-Wings & B-Wings. One can only get so far stealing from breakers yards after all.
They also need weapons. That means everything from proton bombs, to heavy blaster cannons, to small-arms. On top of that you have consumables like food, ammo, all environment combat clothing, battlefield comm-gear, replacement parts, tools, droids, bacta, and a million other logistical needs. And all of that would just be for just a relatively small group about the size of the Phoenix cell.
All of that is just to supply a fighting force; What about the intelligence network? They need money for much more specialized covert equipment. Concealed weapons. Forged documents. Surveillance gear. Underworld slicers. And probably most expensive of all: bribes. You think a frustrated mid-level Imperial bureaucrat is going to hand over classified intel, or look the other way on suspicious shipment manifests for anything less than five figures? Multiply that across the whole theatre of operation and suddenly that 80 million looks like it would struggle to even get Base One up and running for more than 6 months.