I do see there are multiple mistook approach in your questions:

1. For $25k investments, if you look into altcoins alone then definitely you are going to miss out something is proven over the decade of time and known for definite and consistent returns for every four years. Yes, you must include bitcoin as well into your consideration and more importantly in major portion.

2. For $25k investments, you must look for at least 10 different coins and definitely no just 1 or 2 altcoins only.

Including bitcoin in your portfolio will definitely get you the power of diversification but again if your considering more than one altcoins, your risk will get spread out and you will be getting a completely diversified portfolio which will be having 99% guarantee to get you big profits.