For me the true investment is the projects that help Polkadot achieve success.
I invested in $PCX they are providing the bridge between Etherium, BTC, KSM etc ... with Polkadot.
This is what is needed we need to combine the projects and make the good ones better using the new ones.
That is why I am a true believer of PCX.
I do agree that polkadot itself can't succeed without any help. Ethereum is not the second ranked coin because it is great itself, it is ranked second because there are thousands of other coins that is tied to ethereum chain, look at metamask and you will see a thousand different coins all tied to erc20 and that is the reason why ethereum became so big, even defi ones are tied to ethereum as well.
So long story short if polkadot wants to be huge, it needs to have a lot of other projects built on top of it, no coin can surpass ethereum all by itself without any usecase or reason to buy it, people need a reason to buy a coin and if you do not provide them enough reasons it will just become "buy it now so you can sell when it goes up" and that is not enough reason to make something become huge. New things that are being built on top of it will show how good it will be.
There are Huge number of Projects using Polkadot network to create smart contracts,
. The beauty of the network is it uses Multiple chains concept to execute transactions which reduces transaction time substantially. Its popularity is growing with every coming day.