You are deluded af.
I would take any bet that could you time machine the top 20 most highly regarded NBA players back to their youth and put them into tennis instead one, maybe two, of them would achieve anything in tennis. Tennis, like all sports, self-selects based on a variety of factors - some of which are quite specific in terms of mental aptitude for a sport (focus, discipline, quick thinking, problem solving, tactics etc) which would deny most (even legendary) team sports players any chance of truly excelling. There are things you just cannot learn well enough if you're not cut out for a sport even if you might have great physical potential. Basketball is a skilled sport but is also extremely low in technical aptitude required by comparison to tennis. You can coach people all you like but many people simply never grasp things while they might be naturals at other stuff.
People vastly overstate the transferability (is that even a word? lol) of potential from one sport to another. Being tall and muscular aren't skills, they're mostly just luck-of-the-draw things which happen to correspond very well to the nature of basketball (the court size, hoop height, ball type/size, format etc).
I have personally seen, across about an 8 year period, one of rugby's most legendary former players get tennis coaching. He is dedicated, disciplined and not even that old but his tennis has probably only improved from 3.0 level to 4.0 level in that time. In rugby he was considered one of the most all-round talented players ever but if you didn't know who he was and just saw him play tennis you'd think he was almost a beginner - despite having played tennis since he was a teen. He even plays golf off a 6 or 7 handicap apparently so is no slouch in other sports.