You can easily spot scam ICOs, you have to be very cautious with your investment. One way to determine is to invest only in a high volume project and in that way developers will not easily scam you as they believe they can make more money in the future when the project increase.
Meaning ICO whos back up investors are known or trustworthy already because of successful projects they launch before.Community support is also a good factor to determine, if there are people supporting it, it has great potential to succeed.
In question that holding bitcoin to make money, its ok for me as long as you have spare money to spend. As what I have observed that it needs more time the value to appreciate and sometimes unstable.
Investing in ICO gives you a good chance to make a profit if you can invest in a legitimate projects, in LISK ICOI I have participated and I was so happy that I was able to make a decent income in my investment as after the ICO, a good price as available, that is the last time I made money in ICO and the risk of them is not yet an active profit.