I managed with 1 for several years, then upgraded, then bought another, then it got silly. Trouble is that my bikes all get used, some way more than others, but the least used are old and worthless.

Currently:
My old steel Dawes rigid mtb. Set up as a commuter but not used for a year or so
Spesh FSR (2002). My 1st proper mtb, now only used for trail centres. A bit battered and worn
Spesh stumpy hardtail. SS, and bought for £150..... Turned into a race bike but then singlespeeded.
Ribble carbon road bike. My favourite for road use
Planet X Uncle John - commuter and general unloved workhorse
Planet X Dirty Harry carbon 29er. Fast. Fun. Love it
Kinesis Pro6 CX - built up from 2nd hand bits, fun in a strange sort of way
Bill Nickson steel road bike. Needs restoring and I have plans for it.
Gundle butchers bike - nearly finished restoration. Should be a horrible thing to ride but lovely to look at. Will use it once then back of the shed...
I can't think what else I need. I keep dreaming of the next bike to have, but what's the point if I don't use it.

Maybe a path racer type thing, a custom steel or Ti thing. Collection of vintage road bikes (why???)

I have 7 at the moment:
Custom titanium fatbike with 65mm and 90mm carbon-rimmed wheels - from arctic expeditions to general hooning-about
Custom titanium 29+ for when I want to go a bit quicker.
Kuota Kross CX bike
Custom titanium Ritchey Breakaway clone CX & travel bike - for holidays and trips away
Colnago CT1 road bike - getting near classic status now, rides and handles beautifully
Battaglin carbon road bike running fixed gear - stupid light, leg-burner
Gios Aerodynamic - restored retro-bike for special events

I also have a classic Woodrup 531 road frame that I was given and will probably build-up as a retro-fixie with Sturmey Archer 2 speed hub

Seven here as well at the moment, not including the frame that's hanging on the garage wall.
The carbon road bike
The winter/general riding/audax bike
The fixed wheel bike
The on road tourer
The mtb/off road tourer
The CX type bike
The Brompton
And a 1996 GT Zaskar frame that will likely never be sold now - on the garage wall.
There were a couple of others that have been moved on - a very nice handbuilt Argos TT bike (stopped doing TTs) and a Trek FS bike that I just didn't get on with.

3 is too many for me...I have 2 built up and 1 on the side ready to strip parts from bike no. 1. Space is my limiting factor - the stand has room for 2.

Greetz

S.

Without engines
Santa Cruz super light mk1
On one inbred 26"
Ritchey P-29er
Orange Diva "wife's although I may have done a cross race on it "
Raleigh esquire
Early Moulton with suspension
Mid 90's cannondale
Late 90's cannondale headshok ht
90's Raleigh blue ridge

With engines
1955 Triumph tiger cub
1961 Triumph 21
1966 BSA D7

I expect I will appear a bit of a Luddite.

just 4 for me this end,
It takes me at least a year to convince myself I want another one , then longer to buy one
but I use them all at some point, 2 more than others, but all three mtb have 29+ front ends
ti stooge
steel stooge ss
surly krampus
boardman road bike

I had a cull a few years ago but somehow and without me noticing, the number has steadily increased again. In the past, I think I viewed myself as 'having too many' bikes but I now appear to be past the caring stage and will hopefully one day die, leaving a treasure trove of 'barn find' gold or junk depending on your point of view. As long as they're not causing you financial hardship or domestic unease ... you can't have too many

as of last night, i am now the owner of 1 single solitary lonely bike.

To answer the question - too many is when you run out of room to store them and access them easily!

6 bikes and 4 motorbikes for me with space for a couple more of each but no current desires....

2 bikes at the moment use both of them

Currently have 5

Old Giant scr 1 road bike sat on the turbo
New Cube attain pro road bike
Pinnacle arkose adventure - road based bikepacking
Pinnacle Ramin 3+ Bikepacking
On-One 853 single speed , not ridden much in the last 12 months but its a keeper
No more room im afraid :(

Just mine, or family bikes?

Spearfish for summer, racing and multiday fast outings.

Rigid Ti 29er for most other things. 9,000km worth of other things last year just on this. Needs a 2xsetup to make it the divide bike.

A drop bar cx/gravel type of thing that seems sensible but doesn't really get ridden. Winter road bike too, but who wants to do that!

Carbon cx race frame

Steel winter rainy road frame

Summer road bike. A bit fancy, but not matching at all. Mainly ridden in France during summer holidays.

Need a clear out of family bikes. Seem to have road and Mtb in various sizes including sizes no longer required.

I think it's 10 or 11 in our household at the mo,of which 4 are mine but
I only ride one ( 2 are frames and 1 the daughter uses), , my lad has bought
My gravel tourer off me to commute on and has my full Susser as I'm a bit
Long in the tooth for that malarkey now.....the latest addition is a Scwinn
Cruiser, a Mother's Day bargain the kids picked up for her......I've still got
Room for a Fargo and a Moulton apb though