That's not necessarily true. In 2016, when s1mple didn't even have any existing contract, and there was no buyout involved, his contract (without counting salary) was 1 million USD (revealed by s1mple and his brother in an interview). Currently, s1mple's brand is worth millions of fans and viewers and his individual accolades boost his market value immensely. The org only cares about how much money s1mple can bring in. Tournament winnings are usually lesser than the sponsors' money. So, more viewers and fans, more entertainment = more money. S1mple brings that unlike anyone else.
Just to put things in perspective, s1mple literally has 10X as many social media followers as ZywOo. In terms of market ROI, this alone increases s1mple's value immensely.