How do you handle the risk of not being able to resell instances that you've bought back? What if I buy 10,000 instances and sell them back to you after 30 days

How do you handle the risk of not being able to resell instances that you've bought back? What if I buy 10,000 instances and sell them back to you after 30 days? Seems like a competitor could do something like that to intentionally sabotage your business. Though maybe there's so much liquidity in the market that this isn't much of a risk, and in the worst case you could probably find someone you could sell to at a loss.