It's educated speculation on my end. Why would you lock yourself up long term at that amount of money when you can go short-term, bet on yourself, and get lots more money in your next deal?
That has nothing to do with if he actually wants to be here or not, though. It's just their (him and his agents) strategy to maximize his overall career earnings. If he signs 8 years now he's UFA at 32 and we've seen the market someone dry up for players at that age, as teams are worried about how much longer they can keep it up.
So from their end it's probably looked at like....
8x7.5M now and then earn maybe an additional 15-20 million in contracts at 32+ years old
Or
5x6M now and then at 29 sign a 6-8 year deal in a league with a higher salary cap for like 60+ million
Not taking the long term security right now and risking injury certainly is a gamble, but it could pay off with something like an additional 15M+ in career earnings if it works out.