I do not make any investment advice. It is recommended that you talk more with the exchange to understand the truth. Everyone cares about the return on their investment, and they are all greedy. Remember to find the right investment
I am fully aware that the exchanges are not charity

No need to check with them, see the below link for a Business Insider article from March 2018 about listing fees. Maximum for top-tier exchanges was 1 million USD at that time. If they wanted more from you, then something was probably wrong.
https://amp.insider.com/cryptocurrency-exchanges-listing-tokens-cost-fees-ico-2018-3But the topic of top-tier exchanges is not the most important now. As I already mentioned, more important is marketing of existing features, development of new ones and a strategy containing all these things.
And I did not ask for any investment advice. I was just asking what are the long-term goals of DeepOnion you were mentioning.