So if someone makes $5M illegally their penalty would be 5x greater than that of someone that made $1M illegally and both would vary in proportion to how many years of someone's life that represents.
"Federal sentencing is generally based on intended or actual loss, whichever is greater. Further, the judge is allowed to take into account intended losses from his entire course of conduct, not just the intended losses from the specific counts on which he was found guilty."
Criminal A stole $50k from pensioners via confidence tricks. Criminal B was engaged in a complex structure to shelter income; it was eventually ruled illegal and he was found to have avoided $50m in taxes.
These are both financial crimes, but by your logic Criminal B has done something a THOUSAND times worse than Criminal A, and thus if Criminal B gets sentenced for 5 years (a not-uncommon sentence for people convicted of large scale tax fraud) then Criminal A gets locked up for 44 hours.
Conversely if Criminal A gets sentenced to 10 years (a not-atypical sentence for that sort of crime), Criminal B gets locked up for 10,000 years? Or in other words, life without parol; a sentence we don't always hand out to murderers and rapists. For what is very likely nothing more than disagreeing with the IRS about how exactly a loophole in a very arcane law actually works?
By any reasonable metric, Criminal A deserves the harsher penalty. The face value of the amounts tells you very little about actual harm, culpability, chance of re-offending, etc.
In a world where people occasionally steal $100m, that implies a maximum sentence of ~1 year for stealing $1m.
It would be nice from the perspective of reducing the incomprehensibility from white collar crimes that net hundreds of millions of dollars though I'd be concerned about false charges... well, I'm generally concerned about false charges so we just need to fix our justice system, then such a scaling might make good sense.
Just to briefly note, these crimes aren't victimless, people who pull these sorts of stunts are taking money out of someone's pocket, usually fraudulent stock maneuvers will end up negatively impacting retirement mutual funds, sometimes other white-collar crimes may be more impactful, prematurely issuing foreclosures deprives people of their household. In the former case the damage is spread around and less horrific feeling, but both are terrible.