In the beginning (AD&D 1E), it was because I was the oldest of four siblings who wanted to play a campaign amongst ourselves, so the DM role naturally fell to me.
Later, when I had two sons and wanted to introduce them to AD&D 2E, I was the only adult (and the only one who had played before), so the DM role naturally fell to me.
Later on, when a co-worker wanted me to introduce his son to D&D, I was the only one who had played/DMed using the 3.5 rules, so the DM role naturally fell to me.
But despite having been thrust into the role of DM, it's something I've greatly enjoyed and something I would have volunteered to do in any case. And now I also get to play my own PC in another weekly Wednesday campaign while still DMing my own campaign on alternate Saturdays.
Johnathan
Later, when I had two sons and wanted to introduce them to AD&D 2E, I was the only adult (and the only one who had played before), so the DM role naturally fell to me.
Later on, when a co-worker wanted me to introduce his son to D&D, I was the only one who had played/DMed using the 3.5 rules, so the DM role naturally fell to me.
But despite having been thrust into the role of DM, it's something I've greatly enjoyed and something I would have volunteered to do in any case. And now I also get to play my own PC in another weekly Wednesday campaign while still DMing my own campaign on alternate Saturdays.
Johnathan