While I agree, the negative effect with letting it slide after X years would be that you're removing a lot of downside from the risk-benefit analysis of every p

While I agree, the negative effect with letting it slide after X years would be that you're removing a lot of downside from the risk-benefit analysis of every prospective criminal. Fraud is already pretty easy to get away with. If there were a rule that all you have to do to face no consequences is get away with it for a certain amount of time, more people would do it.