I personally do not invest in IOTA because it's market cap is already pretty high.
This is a really bad argument :d Do you not invest/trade in/for BTC?
It's a perfectly legitimate argument, it's one reason I have also not considered investing in IOTA, it has a big market cap already for something that is in development. It doesn't have a huge amount of room to grow in and so many investors may choose to look elsewhere.
The internet of things is in trillion market.