It is Messi. Don't get me wrong, still can't believe it, but he is 33 and would probably only be here for 2/3 years. Giving a guy who has only been here for 3 year a slice of the pie seems excessive. If I was KDB, that would be the first thing I'd say at the next contract negotiations. I am a natural pessimist though, so am a always going to look through sceptical glasses before anything else
There's a reason Messi gets €140m every year from Barcelona and endorsements and KDB gets about €30m.
Negotiations are about what you're bringing to the table and as much as I love KDB the player, his brand is a mouse and Messi's is a hippo.
The equity (if it happens) or however Messi gets paid is only happening because the club will make so much money off him.