Good reason actually. A professional foreign agent of course will have a clean cover, but those guys don't actually have access to secrets. Their job is to recruit people who ALREADY have access to secrets.

Most major spy cases in the last few decades were all about money (not counting social media leakers, who are not technically spies). Many of them were fundamentally irresponsible, which reflected in their finances.

Ames, Pollard, Hanssen, Pelton, Pitts, Walker, etc.