Now, some may argue that BTC is a better investment, which is true; however, do you believe these people do not purchase alternative coins? I believe they do, but they are unlikely to tell you.
Some maximalists may not. But generally, you won't hear from whales "I'm buying XYZ". You'll hear "I bought XYZ". And when you buy because you hear them tell you, they might dump on you.
Buying coins because rich people are buying them is a terrible way of investing. You're right that they might actually dump on one. I strongly believe that some of these guys are actually buying alts, they'll just never talk