The simple point is that he was around to buy all the stuff "cheap" when no one really cared and took care of things that were around but not collected by anyone as they were not indemand. By doing so, be it in Japan in the days when nearly no one else had contacts there, or at John Anderson house, he was able to build up one of the very best collections ever which of course helped him to become what he now is, the worlds number one. As he is not a follower of the "hot box theory" and has loads of stuff piled away it is very likely that the next big thing is in his collection already if he himslf is not even the person to have made it the "next big thing" anyhow.
Add to that one aspect JT already had lighten up, the fact that he is one of the very FEW people who are willing and dare (!) to buy and test something new of course all dealers in the uS and UK know who to ask..
And finally, if there`s a 45 he wants and hasn`t got there is now way you are going to outbid him for example on ebay or whereever...as he doesn`t take no mess...