Assuming your figures are correct I'd be pissed off only getting a £50k return on my £1.5m over 13 years ! I'd be better off keeping it in the bank - it would be easy to make 5% a year meaning in 13 years I'd have made £975,000 pre-tax.
Whatever you think of DK profiteering at the clubs expense...
There is no way the Albion will make huge profits, indeed it's likely they will only break even at best. It's nothing to do with being a Knight licker it's to do with understanding that shares in a non-profitable company mean they are effectively worthless. Even if in 3 years there is £1m after...
He owns 4% of a company that makes losses in seven figures year after year after year. His 4% is worth diddly squat !
And if you really think he's made money so far then you're living in cloud cuckoo land.