In my understanding, investing on IEO's gives the investors a positive viewpoint that the project they're investing in is most likely to become successful thus making their investment a fruitful one. Another thing in IEO, the tokens of the project were already available on the exchange - thus completely eliminating the fear and frustration of the investor brought about by the thought that the investment may not make it or be listed in an exchange.
However, the wisest thing to do before investing be it in ICO or IEO is a thorough diligence so as not to waste our time and hard earned money.
You are right. Tokens or coins that are already available in the market further increase investor confidence to enter the investment. Moreover, ICO's image has gotten worse since many scammers, cheat and take investor money, and tokens or coins have never been listed on the exchange. High investor confidence in IEO is the key to success for development, especially if IEO is carried out on global exchanges such as Binance, it increases opportunities for profit. Even so, the risk still exists, because the price is really determined by market demand and supply.