He’s coming off an Achilles injury. Not hard to convince a guy to take a 1 year deal to rehab with no pressure or need to rush back, get a ring, and then get max offers next year.
This whole GSW dynasty has been built by perfect storms coming together:
• Curry falls to them in the draft (Min took 2 PGs right before Curry) and then has ankle issues which allows GSW to resign him for cheap. He stays healthy and becomes a top 3 player
• Salary cap skyrockets due to new TV deal same year KD becomes a FA
• Cousins suffers an Achilles injury which ruins his FA offers and allows GSW to sign him to the MLE as the best available deal.