It's all about winning a championship. Every championship team year after year has a Top 5 player in the NBA. Just look at the last 10 years and even beyond that and you'll see. You can argue that on a few occasions a championship team had maybe 2 Top 10 players, but no Top 5...sure, I can agree to that.
Basketball is a game where 1 player can truly take over a game and take every shot every time down the floor. You can't do that in any other sport. It doesn't matter how great your bench is, it doesn't matter how great your coach is...it all boils down to that 1 player. (Golden State has two #1's)
Where are the Raptors? Well... DeMar DeRozan is considered to be Top 15 (some saying as high as Top 7, some saying as low as 20). Kyle Lowry is somewhere around the 15-25 mark. Let's just say we've got the 10th best player and the 20th best player in the league. As much as Toronto loves them, that formula is not going to bring us a championship. I think at best case scenario, we can get to the Conference Finals and if our stars perform, we could beat a Philly or Boston, but after being swept by the Cavs in the 2nd Round, it's hard to imagine that since we're basically coming back with the same line-up. The East got better and will only get better.
Kawhi is Top 5 NBA. Some say as high as #2. As for 2-way player, he's considered #1.
Enter Kawhi. Yes, we will lose one of our stars and a few of our prospects and yes, he may only play with us for 1 season, BUT for that 1 season, the Raptors could actually contend to win a championship.
If he leaves... so what? His contact comes off the books and we can look at landing a new player.
If we went to the Finals with Kawhi (which can definitely happen!) don't you think that would increase the odds of him returning?
And even if we don't, maybe Masai can pull a Presti and re-sign Leonard like OKC re-signed George (everyone said he was going to LA!).
For me, no one cares about finishing 3rd or 4th or 5th, it's all about making history and being #1. Toronto, take that shot. If you don't, we'll be mediocre for a long time (which is OK for most people), but not OK for me.
I've been through the Hedo Turkoglu, Andrea Bargnani, Darrick Martin, Acie Earl, Mengke Bateer, Matt Bonner days... those days sucked, but I'd risk going back to that for a shot a championship and landing a Top 5 NBA Star.