You do not need any service or third party to do the listing, all the third party will do is follow the same methods that you will follow and will take an additional commission or may steal more
Yep, they profit from the ignorance of others. Luckily for them, there is an abundance of that on the crypto market on all levels. There are services that can get you listed much faster, but finding a legit one is harder than it seems as majority of them don't have those kind of connections (that means they have to know someone working on CMC/Coingecko) so in the end, its best to avoid them all together.
I would add more. To be listed on CMC and CoinGecko, his project, coin, token or whatever, needs to meet some criteria like trading volume for example. So, even if he pays someone for listing probably will be removed or delisted (especially on CMC) without enough volume. that would be wasted money.
That's true for Coingecko, you have to be listed on the exchange that is tracked by them, but you can get listed on CoinMarketCap weeks or even months before your token/coin gets listed on the exchange. When you fill that form that I provided in my previous post, your project gets listed on CMC as "Untracked Listing" and will stay in that status until your coin/token starts trading, and only if it's on supported exchange with enough volume. The last part is not done automatically though, you have to submit the form yet again.