I wouldn't pay it myself but apparently there are traders who think they have a strategy that can make money even while paying exorbitant SLB fees.
Can you name one?
It's pretty obvious that paying over 100% is a guaranteed loser. (Noting that I mean 100% over the term of the loan.)
My beef is when you said a stock is hard to borrow because of high short interest.
Short interest is the driver. No short, no borrow.
The float is not the same as the number of shares able to be borrowed. For example an employee stock plan might provide matching shares to an employee after a certain holding period. Those shares are not actively being traded but the company administering the plan might be making 50% of their income by loaning other people's shares.
That was a specific case, but more generally, just because the shares aren't being traded, don't assume they aren't being loaned.
In the case of MAXN, I wouldn't be surprised if insiders and institutions are loaning their shares. That could massively increase the available borrowable shares and explain the low cost.
The way I see it, the drivers are:
1) The expected amount of the drop in price
2) The level of certainty of that drop.
People will short until it is no longer profitable to do so. The amount of borrowable shares (not the same as the float) just sets how many people can get in on the deal.
Sure, I recognize it's a market and there are differences of opinion, but not many are going to say "let's enter a trade that is guaranteed to lose money."