It also blows my mind that the Sun accounts for 99.86% of the entire Solar System’s mass.

Makes sense. You have a lot of gaseous outer planets, then a star who's compression needs to be so great that fusion can happen in it. That compression is going to drive up the density of the star.

"If Jupiter were a little bit bigger, we'd have a binary star system!"

<The Sun, massing 1000x what Jupiter does.>