Umm... 2500 refills per day means you would for example need +60-70 buccaneer/siege loots (best loot vs time) with premium per day.
If you do one 2h observatory run with friends and one also having a observatory active, plat horseshoe active and everyone doing precision work with not a single minute lost its at tops 16-18 loots per 2h. However at extreme case you can only activate your observatory max twice per day and if you do that would have to use at least 4 hours of non stop playing each day only get half of that refill amount. During the time you cant buy lootspot or do anything else at the same in terms of getting refills. Rest of the the time you could join observatory runs hosted by others, buy ls and do other stuff but you would have to play actively around 8-12 hours per day.
Unless you want to go more in detail how did you get up to that number per day I think you have a different meaning for the word unrealistic than majority of the TSO players do