The NBA is different than all other sports. To win you need transcendent superstars and you get those, essentially, through sheer luck and possibly a warm climate or a series of brutal, losing seasons that end in the hopes of a ping pong ball bouncing your way.
Just look at the top-tier teams: OKC (two max-type players and another borderline max player), Boston (planets had to align to land the big three and only that happened because McHale is a terrible GM and apparently owed someone a favor at TD Garden), San Antonio (the greatest power forward in NBA history, the greatest sixth man in NBA history), Chicago (a perennial MVP and someone who can potentially become the world's best player), the Lakers (the best player on the planet for the last decade or so) and, of course, Miami, a fraud sports town that boasts great weather and a beach full of semi-nude supermodels that benefited from a free agent conspiracy, which caught GMs across the league completely off their guard and forever changed the way free agency applies to superstars.
Teams like the Sixers, Pacers, Jazz, they play hard and have role players and drafted okay, but does anyone really think they're going anywhere? The NBA isn't hockey where grit and determination and physical intimidation can overcome talent, which is why I was always in favor of trying to get high-level talents here. That's what Melo and Amare are, or, at least, what we hope them to be. They may not be enough to ever overcome the Heat and Bulls of the world, but what's the alternative?