Tell that to the Spurs, who won a title with and old and fractured Tim Duncan / Tony Parker and an up and coming Kawhi Leonard who (up until the playoffs that year) really hadn't made much of a bane for himself.
Also tell it to the Lakers, Sixers and Celtics who have all had multiple lotteey picks in the last few years and have no "Lebron" caliber player yet to show for it
Or the kings, who (in some 10 years of consecutive lottery picks) have only drafted two guys who could be considered superstars.
If you're going to throw all your eggs into the draft then you had better head lottery picks guaranteed for the next 5-6 years at least if you want to give yourself a half decent chance.
Or you can just trade for a guy who is already a superstar, and isn't even in his prime yet, like Jimmy Butler.
Both of these statements are true:
"Teams that win championships do so with drafted players."
"Drafting a superstar and then winning a championship is incredibly difficult."
The plain fact is that the vast majority of rings in the modern era have been won by teams with a home-grown superstar. Bird, Magic, Jordan, Olajuwon, Duncan, Kobe, Dirk, Isiah, Steph. That's 27 out of the last 37. That doesn't count Lebron's Cavs, Wade's Heat, "Shaq's" Lakers, etc. where there might be some disagreement. Even the others had plenty of home-grown talent (Kobe, Pierce, Dr. J.).
Detroit is the clear exception, but one data point is an outlier, not a counter-argument.