So the current proposed cost of an arena is over half their total wealth and the vast majority of that wealth is invested in business assets, including the Kings franchise. Its not available in the form of cash. They'd have to borrow a heckuva a lot to build it on their own and no lender would do it, because the cash flow sucks and will hardly support any debt payment.
That's similar to saying your house is worth $300,000, so you can afford to buy a a yacht for $175,000. Of course, you'd have to borrow and of course, if your cash flow sucked, you couldn't make the monthly payments. No lender would touch the deal. Well, except for the guys that will give you cement shoes if you don't pay up.