many moons ago I had a sh#t job and not much money, so economics dictated that I could only have one bike. Orange Clockwork – couldn’t drive so no car, worked shifts so no bus/train. Used to run worn out nobby tyres as semi slicks during the commute and then remove the mudguards and rack and fit decent tyres for the weekend rides/races.
So it’svery doable , but to be honest its a proper pain in the ar#e – getting back from an epic ride on a sunday evening knowing that before you go to bed you’ve got to clean the bike,change the tyres, fit the mudguards/racks etc. ‘cos you’re back out on it at 5am, can be a bit dreary, especially mid winter when its raining.
I’ve now got a better job, 5 bikes (can drive but choose not to).
TBH – two bikes is probably the best option, one to fuel your passion (either very nice road bike, or very nice mtb etc.) and one for the daily grind ( in my case a Kona Sutra, for the commute, shopping, and some camping trips and a Sanderson Life for real off road riding etc. Theother 3 are more sentimental value , Clockwork that I’ve had for ever is now SS, Scott racing hardtail,son uses it and cheap road bike on turbo trainer – probably gets more use as a clothes prop TBH)