That may be all you need. For social media, with everything you upload cut down to 1–2 megapixels on many services, you may not care about better images. The P900 and P1000 do seem to have a cult-like following. These are the right cameras for some people.
Any system camera is going to deliver more flexibility and far better images than the P1000. But not in a single lens, of course. I have been using Olympus Micro Four Thirds gear for years, which is highly regarded for outdoor shooting and for telephoto lenses that are still affordable by non-professionals and long enough for sports, wildlife, etc. Of course, Canon, Nikon, Sony, Fujifilm, Pentax, and Panasonic all have their own interchangeable lens systems. There are advantages and disadvantages to each. It’s not a thing to jump into in a hurry, and it’s going to cost an order of magnitude more than a P1000 to build out a decent system.
If you think you need a 3000mm lens, buy the P1000. I can get the 35mm equivalent of 1600mm via my Olympus M.Zuiko 100–400mm lens and the MC20 teleconverter. I can technically get to 2400mm equivalent using a 600mm lens I have from the 1970s (Vivitar One Solid Cat 600mm f/8) plus teleconverter, but that lens isn’t a sharp lens even without the teleconverter. With the teleconverted 400mm, I could crop to “3000mm” and get a better image than the P1000, but then again, at $1400 that lens costs more than a P1000, and you’re in another $400 for the teleconverter.
Canon makes 1200mm f/8.0 lenses for both their SLR (EF) and mirrorless (RF) camera lines. You could technically turn this into a 2400mm lens with a teleconverter, but you’ll be taking an image quality hit. This lens runs around $20,000 too, though you can get the 800mm f/8.0 for only $17,000! Though with ILCs, you always have choices. Canon makes a pro-grade 100–500mm zoom lens for the R system, priced at about $2,900, and a consumer grade 100–400mm zoom for about $600. You also have various choices from third party lensmakers.
If you’re looking for a superzoom bridge camera with a better image quality, go for the Sony RX10 Mark IV. This camera has a lens that varies from f/2.4 to f/4.0 across a 24–600mm (35mm equivalent) range. It’s based on an advanced 1″ stacked sensor from Sony. That delivers very good image quality, though of course, not the barking mad zoom range of the P1000. This is also more expensive than the P1000, but worth it if you’re more interested in image quality than zoom range.