When testing the waters of "how much I need to retire", the 4% rule keeps coming into play, however I'm not sure I'm following how this works.

My basic understanding is to take the amount you want to withdraw every year (i.e $30,000) and then divide by 4% = $750,000. Is this telling me that once I have $750,000 of available money invested smartly in the market, I can retire? And is this an "infinite" retirement? Say if I retire at 35 with $750,000 of available money I can never work again until I die?

Just trying to get a little more layman's clarity around this. Thanks