Perhaps I can educate you a little further about the academic world.
There are indeed constraints other than one's own personal or professional virtue. The principal one is that if your work does not convince your professional peers, it will not get funded or published.
You can't just invent a bogus research program out of thin air, hold a press conference, and expect to get hailed as the new Einstein.
For example: claims of cold fusion, room temperature superconductors, and similar marvels appear fairly frequently and are quickly knocked down because experts in the field can tell they are false. (NB these are not necessarily frauds, just bad science.)
There are also institutional constraints provided by the universities and professional societies to which academics belong.
Scandals about plagiarism and fraud only hit the news when these institutions take action against senior academics. This typically only happens in the worst cases where there is a clear pattern of behavior and the guardrails have obviously failed.
IMO long running and successful frauds like Cyril Burt tend to already have the benefit of a well-earned professional reputation, but have gone about boosting their credibility in an unethical way.
Small bore fraud is hard to catch. It's like padding your resume. If you say you won the Nobel prize, people will smell a rat. But a lot of it probably gets under the radar.