No Regrets On $3 Mil McGwire Ball

Here's how you KNOW you're rich -- when you drop $3 mil on a baseball that later plummets in value, AND YOU JUST DON'T CARE!

Case in point ... Todd McFarlane, who's explaining to TMZ Sports why he's not remotely bothered by the fact his Mark McGwire #70 home run baseball is only worth a fraction of what he paid for it.

Remember, Todd -- one of the most successful comic book artists of all time -- bought the record-breaking ball in '99, right after McGwire and Sammy Sosa wrapped up that famous home run chase.

Demand was high at the time -- but the steroid scandal (and Barry Bonds) caused the value to sink like a stone. Multiple experts say the ball is only worth around $300k to $400k these days…