I wonder if that feeling is universal?
I think it is, broadly speaking.
When I started, I just bought an MVS MV1FZ motherboard, a 138-in-1, dipswitched it, consolized the board, made my own replica MVS Sticks and connected it to my Sony BVM and I've been playing all the Neo Geo games I've played as a kid for months.
Afterwards it kinda died down a bit on me, until I got my SEGA Astro City Cab which sparked my will to play all those games again the way they were meant to be played and so I kept playing for several months and then down it went, due also to time constraints/real life issues.
Then came the System16B board for which I've bought an EPROM programmer and chips and played lots of Altered Beast, Shinobi, Golden Axe, etc...
Then came the Taito F3, then CPS2... now I've been patiently waiting almost 3 years for aje_fr to ship his CPS1 multi and the cycle continues.
In the end, I've just kept my 138-in-1 cart and the EPROM chips for the System16B system and CPS2 and I'm thinking of selling my Taito F3 which doesn't see much use as of late.
Guess that when I'll have the CPS1 multi I'll be again busy for several months with SF2, Ghost n Goblins, Knights of the Round, 3 Wonders, etc. and then go back to go finding something else.
Meanwhile, I've got back into analogue photography (developing and printing my own photos at home), learning classical and electric guitar and a bunch of other things.
We all get excited at first then it slowly fades away as time passes and our attention goes to other things.
I think it's pretty normal.