Like the CMDRs above, I enjoy having my carrier. As said, it is a mobile base and I can take my fleet with me everywhere I want (provided there is parking space). My carrier has never really left the bubble further than 1k Ly, I don't take it out for exploration, so fuel consumption is less of an issue for me.
Regarding the running costs, I have rearm, reful and repair, UC, Vista and a bar active. My weekly upkeep is 14.6 million plus the jump maintenance costs (100k per jump?) - I do a handful of jumps per week at most, in some weeks none at all. I bought my carrier when void opals and LTDs were still a thing (and I think it was before the bulk tax), and as I love core mining it felt pretty easy to manage. These days the fastest way will probably be AX combat or exobiology.
I have parked 1.8 billion credits on my carrier, which will cover it for over 2 years - carrier upkeep is taken from the carrier balance, not your personal one. If I need Tritium, I park it near a station with a good supply and low price and put out a buy order for 150 to 200% galactic average. Last time I did this I put out and order for 5000 tons, and it was filled in less than an hour. CMDRs still go crazy for credits and fuel your carrier really quickly if the pay is good (it cost me 500 million, but I'm rich, I can take it

).
If you are still struggling for credits, the upkeep is a principle issue for you or the effort you have to make to earn it bothers you, then a carrier probably isn't right for you. In that sense the carrier can be called kind of an "endgame" asset, because at a certain point you will have so many credits that you really could care less if the upkeep is 14 or 40 million. I surely don't, I have 8.7 billion on my CMDRs name and, as I said, 1.8 billion on my carrier, and these days the credits to finance the upkeep for a year are really easy to make if you find a well paying activity that you enjoy. These days I make very little credits, but when I do feel the need, I still go core mining (Grandidierite has been pretty stable for me and usually pays at least 500k per ton, which means a 80t load gets you around 40 million, and it usually takes me around an hour and a half including selling), or I go bounty hunting (a relaxed hour in a HazRES usually gets me the week's upkeep, much more with massacre mission stacking for allied factions). Both are activities I enjoy immensely, so I don't feel it is a grind or "work". Some complain it is like a "second job", and all I can say is: If it feels like it, don't get one.