A personal title is a one off payment and shows a certain commitment. Other sites, e.g. Friends Reunited, expect you to stump up every year, if you wish to be a full member.
The forum was started as a hobby, discussing aviation matters. It was never meant to be a commercial concern but DF had to ask for financial assistance to allow the site to continue because of the ever increasing cost of the bigger and better equipment required to allow sufficient bandwidth.
IMHO, Danny made a slight mistake back then because he should have made it mandatory to contribute financially. Somewhere along the line, a huge number of contributors decided to jump on board because they didn't have to pay anything for posting privileges.
My suggestion would be to require a small payment to post or to access certain areas of this site, which is quite normal these days for many other websites dealing with technical matters. That will sort out the bandwidth problem.
I'm a member of another engineering based website, based in USA, where the originator has no qualms about telling contributors to go away if he feels a post (even a genuine question) is not up to his standards. They get a very terse reminder to use the search engine and go away.
The severely piqued ones claiming to de-register are cutting off their own noses out of spite and won't be missed. I can almost guarantee that they will still be out there, unable to resist the temptation to take a sneaky look.
P.S. Beagle, now you're no longer an impoverished military pilot, it's time you got your hand in your pocket, too. Only about a quarter of a tankload of fuel for that musclecar of yours (that you so much enjoy telling us all about) would do it.