I'll take this from another angle. I'm not a lifetime Celtics fan, I came over with Kevin Garnett. But just picture how DEPRESSING it was to be a Kevin Garnett fan for the past 13 years:
The most talented player he ever played with, Stephon Marbury, jumped ship after 2 seasons due to jealousy and money before either could mature enough to compete.
The best player we got in the Marbury trade, Terrell Brandon, quickly becomes injury prone and had his career end on the injured list 3 years later.
The owner and GM get caught in an illegal signing (for Joe Smith, of all people) and costs the franchise a generations worth of draft picks.
Garnett's best friend/idol and probably the best SG on the Wolves during this period, Malik Sealy, dies due to a drunk driver going the wrong way on the highway ON HIS WAY HOME AFTER KG'S BIRTHDAY PARTY.
The one time there is any modicum of talent on the team, Sam Cassell gets injured in the WCF to derail a possible title run.
I could go on with this, but the point is that for a solid decade it seemed like the basketball team that I lived and died with every night was outright cursed. Seeing KG go to war against Shaq/Kobe with Troy Hudson as his second best player...it just was not fun. So to go from that to seeing him able to go to war every night with Pierce and Allen, to being able to pull for a team that wins with teamwork, unselfishness and relentless defense, to watching them earn their place in the most storied franchise in NBA history...watching Bill Russell (!!!) adopt him like a son...to FINALLY win a ring, and to do it against my least favorite player in a marquee Lakers/Celtics final...it's like overload. It's too much.
In 2007 when the Wolves lost the lottery coin-flip with the Blazers that led to the Blazers getting the #1 pick and the Wolves getting Corey Brewer, I NEVER would have expected that 2 years later KG would have a championship ring and be challenging for another. It's just too cool...