Very roughly, 0.03% of tax cheats were convicted for tax crimes (as of 2017, before the IRS budget was even further cut by Republicans)
If you are being investigated by the IRS for fraud and tax crimes, consider hiring the best tax lawyer you can find.
taxattorneydaily.com
Also, the gun possession charge is quite likely based on an unconstitutional law (at least for anyone else that brought the case up to the current Supreme Court), as the founding fathers did not consider prior drug use as a reason to restrict the pre-eminent constitutional right to own guns. Which is part of reason the prosecutor will likely continue to seek a plea deal.
And except when said gun is used in an active crime, this charge of illegal gun possession or lying about being a drug user is almost never brought. Even though about one in 8 Americans when surveyed admit to the use of illegal drugs, which works out to roughly 10 million gun owners that would be in violation of the same crime that Hunter was charged with. Of which I read a couple thousand may be prosecuted. Call it another 0.02% type odds of being prosecuted, roughly.
Hunter should play the lottery...