17mb is a very large size for a model, and i'm sure most of that detail is not noticed at the ranges you'd see it. Most of the size is usually taken up by texture maps, and a compressed 1024x1024 map would probably end up at somewhere around 1mb. All pbr maps combined (albedo, normal, occlusion, roughness, metallic) would be around 4-5Mb (single-channel textures like occlusion are usually smaller though, and compression may vary), and the model size would reasonably be somewhere around 2-3Mb for the average model with animations. I'd say closer to 6-9 Mb is reasonable for a user-made model, depending on quality. File size optimization has obviously not been a concern with these models, and the animations are probably resampled from IK with a very high fidelity.