I think this is because when you participate in the program for 12 months, the user receives the largest percentage of profit.
When people lease tokens for 12 month they have a bigger profit but the risks are bigger too because the market conditions can change during 12 month.
Everyone chooses a path in investing. If you do not believe in this or that project, then maybe you should not invest in it.
It is also possible to lease the tokens for 3 month and 6 month but people prefer to lease for 12 month. It is very risky because cryptocurrency market is very unstable.