Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
The transaction you are asking about consists of many prohibitions. The person who gives money in order to gain more money provided he brings two new customers and he will get back the same amount if he does not bring the customers is nothing but a loan to achieve benefits which is forbidden in Shariah.
If one gives the amount knowing that he will not get his amount but he will get the prescribed amount (twenty four thousand) only if he brings the customers this is also forbidden since it is a kind of gambling which is forbidden in Islamic Shariah.
In fact, the money gained by usury or gambling is forbidden for the Saying of Allah: {…Intoxicants (all kinds of alcoholic drinks), gambling, AlAnsâb, and AlAzlâm (arrows for seeking luck or decision) are an abomination of Shaitân's (Satan) handiwork. So avoid (strictly all) that (abomination) in order that you may be successful.}[5:90]. Also for the verse: {O you who believe! Eat not Ribâ (usury) doubled and multiplied, …}[3:130].
Therefore, one should get out of this practice and avoid any involvement in such transaction. On the other hand, we encourage our Muslim brothers to invest their money in business or any lawful project in order to gain the lawful benefits instead of Haram money.
Indeed, the rulings of Shariah consider the significance and the nature of the transaction rather than considering its names and titles. Also the consent of people does not make an unlawful practice lawful since many Haram activities are carried out by the consent of people.
Allah knows best.