More damage is being done by idiots than by swindlers every day, and only idiots would invest in a convicted swindler in the event she does leave prison early to become the pretty face of yet another dodgy startup. Letting her loose is a win
That encourages more swindlers. You'd be punishing people for being stupid, while changing nothing. Remember, about 17% of the population have an IQ of 85 or less, for no fault of their own; and fully half of the people have an IQ of less than 100. You should not punish stupid people for being stupid; it is not a choice. It cannot be "fixed", because it is part of our biology.
In comparison, smacking the swindlers hard will at least deter some of the future swindlers. Not all, because most of them are only smart enough to swindle but not smart enough to learn, especially not smart enough to learn from others, but some are. The more lenient the sentencing, the lesser the deterrent, and the more the entire population will suffer.
Also, don't be fooled into thinking you need an IQ of over a hundred to become an investor or a politician. That is demonstrably false. In fact, for men,
over-average height is a much better predictor of political and financial success than IQ.