That is because in investing, you are contributing in a project that is already successful but the decision of making you money big is you but in ICO, you are depending on the project itself if it is going to be successful and if it is successful then it is good for you but if not, you just wasted your time. It is all about taking risks. We are all taking risks here and different styles we are using to earn money. Some are preferring on investing but some wants to mine coins and other people wants only to join ICOs and support a particular project and earn money. It is all about being expert on what you are doing because if you are good in trading why you need to join ICO if you are expert on that. Maybe you can do both but you should manage time and everything.
Aside from that, this is because we do have different mindset, priorities, like and dislikes, for some it is easy for them to set up mining rigs as this is their line of work, for some, they love investing as they love analyzing numbers, market and they do have time to do this and this fit their preference. So, for me there is nothing wrong with it, for as long as we are doing something that our future will thank for whether mining or investing, both has potential to make money.
I also think this is more about preferences than anything else, mining may seem attractive to some if they have low electricity costs, this is not the case where I live and I do not want to worry about the depreciation of my equipment and worry about when to replace it.
And while I do not invest in icos I am a small investor and I prefer many times to do that than to mine coins, but I also understand those that like mining may not like to worry about every single movement of the market and what it could mean like I do.