I’m not convinced anyone described monopoly as fun
If you don't add all the house rules all kids use to prolong the game, it is quite playable.
For some reason alot of kids love it. I think handling money is the main lure.
And yeah, getting money and property is fun! But the game is supposed to be a 30-45 minute experience.
The solution is for families other games which are better suited especially for younger kids. But Monopoly has established itself as universal family board game.