I have the ability to go to training camps, participate in competitions and practice every day if I want to.
Most criminals don't have complete unfettered access to those training resources. I think they do train but they do so at the risk of being caught by the police - either trespassing on someone's land or shooting in an abandoned building.
I wouldn't say they are bad shots, but I think it's fair to say that they don't have the opportunity to train like a law abiding citizen can ( I'm not counting NYC or Chicago).
Here is my other point. The anti-gun crowd is always talking about stricter gun laws - but they NEVER talk about stricter sentencing for repeat offenders and felons using firearms. And I don't remember the NRA really pushing it either.
I think if a felon wants to practice with a firearm they're not supposed to have in the first place - then they should do it at the risk of going to prison for 20 years if they're caught.
There are always going to be criminals who aren't deterred period - no matter what. I don't know what school of criminology came up with the classification of the incorrigible criminal - I've seen it in Gary Kleck's writings. I’m not arguing that more gun laws are going to deter criminals who are already breaking laws – including gun laws. But maybe felons who are determined to arm themselves should just be incarcerated period. It seems that Florida implemented similar laws and they seem to have improved things.