Maybe reduce the physical size of your cellar - convert half to a gym...
When I was working up to retirement I aimed for about 10 years worth of wine in the cellar - that's about 3,000 bottles for me as I have a partner who does drink wine, with similar tastes to me and many thirsty friends.
Ten years later it's still at that level, so I have to live at least 10 more years if I stop buying now. But my partner is 11 years younger than me and I need to leave some for her and for the wake, so I can keep on buying for a while yet.
In my case my cellar is sized for just over 3,000 bottles, 3,500 at an absolute maximum, - stacked bottle-on-bottle in bins or standing upright, or in original boxes. So when the regular storage space is full and the pile of boxes just inside the entrance get in the way I stop buying for a while.
I can continue sometimes with the buying addiction if I need to stock up for quaffer packs that I put together for friends or if we have some wine group tastings or dinners where we dig into older vintages from my cellars, that can quickly go through a couple of dozen and I usually only charge them my original cost price.
I usually send off a pile to Langtons once or twice a year, in recent times mostly cork-sealed wines as I try to reduce the remaining number in my cellar. Some I lose money on, some I make money on, I generally come out just in front after selling fees. It's illegal to sell wine to friends or others without a licence - but it happens and nobody gets hurt.
But the key is to be more brutal in your buying decisions, in my case focussing on new release wines that will definitely cellar as I have plenty of 10-12+ yo reds that are ready to go, enough even for week-day drinking and younger ones that need to be tried to assess how they are going. If you tend to be an impulse buyer, make a check list of the characteristics of the wine(s) you need to improve your cellar, keep it up to date and always assess a prospective purchase against the list.
To know what you still need to buy to improve your cellar you need good records of what is there already (Cellartracker or something else, I have a home-grown system that suits me) and work out a plan for the future buying.