We acquired a 24ft pool with our current place. Fortunately its in a building so its usable for more than the week or so in the year its warm enough in this country to swim outdoors without a wet suit. Apart from a new pump (£400) it hasn’t cost that much to run as we only use it April-Sep and only heat the water and not the building. Its easy enough to maintain the water chemistry. Our pool is lined however and I’m looking at a £4k bill to replace the liner in 5-6 years. Hopefully we’ll have moved out before then.
With pools its very much a case of use it or lose it. If you don’t keep them maintained then they will just turn into an algae infested swamp. If you empty them then the liner (even a concrete liner) will float out of the ground if you have a low water table.
If the OPs pool needs all the plant replaced and is an outdoor pool I’d pay to have it filled in. If its an indoor pool its probably worth rescuing.