Does a single-person LLC allow you to "leave money in the LLC" and only pay taxes when it's withdrawn?
Technically Yes, if you elect to taxed as a c Corp. But, this means you're taxed twice. Once on the income left in the c, and then again once you take it out as a dividend distribution.
Overall you can benefit from lower tax rates. But this whole thing should only be done the proper way under proper guidance.
Only makes sense in limited situations