As said above, most of these guys do it for fun. They get a kick out of wasting an escorts time and also talking to us.  Then when the excitement has passed they cancel but now I always know which ones will do that so I do not even class them as booked. Ijust save the number under twat and move on.
Some do book and cancel 5minutes later as they lose their nerve.  I had an old guy do this to me.  His wife had recently died and she told him to never love anyone elese (selfish bitch) but he can have sex with people (so nice of her) so he booked me and cancelled.  he did this twice so the third time he rang I gave him a right telling off which is when he told me his story and he did eventually get the nerve to visit and is now a lovely regular.  nerves can make men cancel so easily
Can you imagine if you were a man, having to ring and book for sex and then turn up and strip off in front of a total stranger and give them money for sex.  It must be so nerve racking.  I could not go through the feeling again.  Remember the first time you escorted how nervous you were?  I cancelled my first couple of bookings as my nerves got the better of me.

Unless they explain why they cancelled you will never know and tbh it is not really worth worrying about.  Only worry about what you can change and forget what you cant.  For every timewaster there is a lovely client waiting to see you.  Use energy on them not on those who let you down