Try reaching a stat level where it becomes competitive stat-wise with the pets you already have without buying feeding items, and then tell us how feasible it is. Getting ultra-rare feeding items is a major pain, especially if you can’t directly buy them. I was lucky enough get the caracal very soon after it came out, and was able to push it to level 20 while it was the only ultra-rare pet in existence. However, ever since I was unlucky enough to get a second ultra-rare pet, the drop rate for caracal feeding items halved, and my leveling progress has completely stalled out for over a year and is unlikely to resume with the way things are currently going. There are other ultra-rare pets that I fortunately haven’t gotten yet, but they would make the situation even worse if I did get them. I have never seen or heard of any F2P player who managed to fully level an ultra-rare pet, and I personally doubt there will be any until at least the next decade. That being said, it shouldn’t be hard to see how spending extra money would give you a major advantage in the pet game.