ICO investors are not decreasing but rather becoming more knowledgeable in crypto. Investors used to enter the market blindly, throwing their fortunes on any ICO. Now, investors know how to research and come out with good ICOs which are feasible enough to be successful at the end of the day.
Agree with you mate, Investors now are more vigilant and knowledgeable due to many ICO's are failed or become Scrammed, they've learned from their past mistakes, but for me, I think its not advisable for now to invest in any ico out there because of the unstable marker condition.