Buying Ether vs erc-20/Ethereum Tokens

[magic_burn]

Hi there,
I was wondering if, exists some kind of correlation between Ether and all the other icos/coins based/used on Ethereum.
Like, from a point of view of an investor, isn't more valuable to buy Ethereum directly than, for example, Golem ?

Because, the way I see it is that all stuff based on Ethereum, even if has value on it's own, it should boost indirectly Ethereum itself due to use their network, servers, etc
Am I wrong?

regards

[magic_burn]

Forgot to add: I guess that if ether price goes down it will also make all coins based on ETH go down too right? As i guess would be the same correlation as on the inquiry of my first message.