MM means you flew 1 million miles, roughly 2000 hours in air. There's no spend requirement, other than obviously you have to buy those tickets somehow. But there's no difference between flying 1MM in business or 1MM in coach, though the former likely requires 5-10x the spend. Everyone's equal to hit 1MM.

Drilling down on "spend" you'd need somewhere north of 5 million RDM to fly 1 million BIS. To get to 5 million RDM would require at least $2.5 million in card spend (not getting 3x since you're not buying united flights), probably much more because 2x miles aren't for everything. I wouldn't be fussed by someone hitting lifetime 1MM with that card spend . . . and still sitting on a plane for 1 million miles like those who pay. Indeed, you likely could make it with much less spend on cash UA tickets (eg. 50 coach R/Ts to Singapore at $1000 each). Even the alternative of having, say, a spouse who's 1K spending $500K to earn those miles by flying is something United likely would welcome and hardly cheapens the accomplishment.

Just doesn't seem like a loophole that people somehow can get to 1M more easily and cheaply via award tickets.