Boasting is required in his line of work, that's how they build street rep, sell their products/services, and recruit people. (Contrast this to spycraft where the acceptable amount of boasting is zero.)

What did him in was boasting from a non-clean slate identity among other things. He needed strict separation between big time jobs which require an absolute clean slate because all the attention will be there, small time jobs that are likely numerous and sloppier but no one will bother to investigate, and pleasure. He didn't have that.

Remember kids, only break one law at a time. And once you're done, shut the hell up!!