Both excellent points. If it's money you can go 30 or so years without touching, you should absolutely be putting it in a 401(k) or IRA. If it's money you think you might need in the next couple years and you've already got a safe $10k in the bank, I'd probably still go with a taxable investing account, but NOT at the expense of your retirement fund. It will bite you in the ass hard later on if you put off saving for retirement.
At a minimum, maxing out a Roth IRA each year ($5,500) is always better than putting that money in a taxable account or a bank account because you can withdraw the principal at any time. For other retirement accounts, you really just need to say "bye for now" to the money because there are penalties if you try to withdraw it before age 60. That's from memory so confirm that somewhere before doing it.