You are overlooking the simple truth. If you don’t save the money it will be taxed at your personal highest rate, as high as 37%, whereas if you choose to save it it will be taxed at a rate of 10%. If you would think letting the government take almost four times as much of your money is fine, well...
So you're assuming:
- this person is making at least $500,000 a year now (to be at 37%)
- the person will withdraw no more than $19,050 a year in retirement (to be at 10%)
- tax rates won't rise significantly between now and retirement.
- tax treatment of 401(k) plans definitely won't change in the future (e.g. there's zero chance that a future government won't start taxing them in some way).
Do I understand you correctly?
If so, do you see why I'm questioning these assumptions?
In reality, what often happens is something like this, ignoring inflation:
- a 30-year-old guy is making $50,000/y (so 22% marginal rate for 2018).
- he has grand plans to make $500,000/y before he retires.
- he follows the standard (but IMO questionable) advice of living on 70% of his pre-retirement income in retirement: $350,000/y (35% marginal rate)
... so any tax savings he gets from his 401(k) now will end up costing him
more when he withdraws it. And that's even before asking if tax rates will go up before he retires. He would have been better off putting his money into something where he pays tax at the front end and doesn't pay tax on the increase (i.e. a Roth IRA in the US or a TFSA in Canada).
In any case: remember that our income - and therefore our marginal rate - tends to go up as we get older. It's very common for your annual withdrawal in retirement to be closer to your salary immediately before retirement than to your salary when you just started in the workforce.