Alot of people blame pet owners that let their snakes go when they got to big for the snakes in the everglades but there is a lot of research out that that doesn't support this. For one snakes that have been raised in captivity and only know how to eat what is dropped into their container and has grown that big wouldn't be able to survive in the wild for very long. Granite they would survive for a while but not long enough to start a population. They wouldn't be able to hunt as well to stay alive they are too used to be handed food. Now im not saying that some wouldnt survive but not enough to reproduce and to the number we have today.
What is more likely is the there was a large shipment of a few thousand baby Burmese pythons that came in Florida just before Hurricane Andrew in 1992. A very large snake breeding facility was destroyed during Hurricane Andrew in 1992. This breeding facility was located just 5 blocks from the Florida Everglades. This is one of them that just received one of the shipments of Burmese. As babies they would be able to start fresh just as they would in the wild and wouldnt know any better or be lazy.
Now im not saying bad owners don't release their snakes which they do and they shouldn't. Just not enough to contribute to what we have today.