Conversion is for religions that preach love and equality which is unfortunately alien concept for Hinduism.
Since what they call Hindoos are actually just a handful of upper-class savarna north Indian males it’s almost impossible for them to cast an illusion of being in majority.
So why are the Hindoos (so-called) scared of conversions?
Well because they can’t lure people of other religion into theirs by saying come join our religion we practice casteism, racism, inequality and untouchability and our Gods did some questionable deeds.
So what they did? They borrowed an Arabic word Hindoo and declared all OBCs, all Dalits, all aboriginals, all Buddhists, all Jains and all Sikhs are Hindoos.
Its the only way the minority Savarna males can trick others into believing that they are in majority when in fact they are the smallest minority.