To do this you would have to have multiple VPNs as well as multiple credit cards/banks with different addresses. AIRBNB has had every scammer in the world assault their site, so they are well aware of all types and frauds on the basis you outline. They can ID VPN's and might smell a rat. In addition, marshalling all these address, VPS's, credit cards is a daunting and costly task = one you can easily screw up. In addition each card/bank you have another thicket of AI to try to get through.

If the competitors decide to sue, you would at the very least be on the hook for damages, and most likely their legal fees as well. And you open yourself up to criminal fraud charges.

AirBnB will ban the accounts you use to do this.

They will if it's obvious. But I don't think it always would be obvious.

If you plan for this to be a recurring component of your business model, the pattern of cancellations will get noticed.

Don't you need a credit card to reserve a booking? You will have to keep making throwaway credit card numbers with fake identities. That's something that can be investigated.