People on ebikes with large egos

Cycling to work this morning when some plonker on an ebike tried to fly past me when the lights went green. I didn't pass any remarks and passed him on the way to the next junction. Again lights went green and he flew past me again as if to prove a point. I let him gain some distance then said enough is enough. I dropped the gear, upped the cadence got set on the drops and absolutely bombed past him, I looked back and he was breathing out of his arse trying to keep up. I then eased off and ensured to stay just within reach but always ahead of him. I don't know why people feel the need to turn a commute into a race, especially on a bloody e-bike that does the work for you.