Welcome to FlyerTalk, Malarchy.

Lounge access (on days you're flying internationally only) is typically only available in the second-tier-up elite status, and thus in liftetime status turns only after flying 2 million miles with a particular airline (it may or may not count certain partner airlines). That's 20 years of 100k paid flying (not 100k earning) a year, or 40 years of 50k paid flying, or 80 years of paid 25k flying a year.

Meanwhile, you can buy lounge access (for one airline) for a few hundred dollars a year. You can get speedier things just by holding the credit card for that airline.

So unless you're "naturally" flying 100+ (paid, not award) miles per year, and doing it for a long time, it doesn't seem practical to "pursue" lifetime status with an airline (any more). (Lifetime status at some airlines worked differently in the past, but that's the way it works going forward.)

Meanwhile:

You seem to have to gotten things backwards. Many of the benefits of status (international lounge access, speedier things, etc) are also available when flying business class or above. Fly your longhaul flights on business (or first) class awards instead of paid coach and you don't really need status that much. And it's far easier to fly several longhaul flights a year as business class awards than it is to get lifetime status at an airline these days.