i believe religion was invented to make ppl scared and have followers
Who would have invented religion from your studies?
The OP stated that those were her beliefs, you added the "studies" part so I'll add an answer. Primative peoples who attributed thunder to 'thunder g-ds', rain to 'rain g-ds', (or 'g-ddesses'), invented such concepts out of their own fears and ignorance ... these ignorant superstitious beliefs became more and more elaborate until some early goat-herders couldn't keep up with pantheistic multiple g-ds/g-ddesses and "invented"
monotheism, (one hypothetical supernatural egregore at a time).
Why would it be invented to make people "scared?"
That's because 'fear', (or the religious misnomer, "awe"), was found useful in controlling the masses, (as noted historically, well before communism's mention of the tool). A large number of people are afraid of various things ranging from death to any number of lessor things and latching onto a superstitious religious belief which deceived the believer into seeming to alleviating, (through deceptive promises in this life and 'the next'), seemed easier for many of the fearful.
Why would there have to be followers? Thanks. 
Without followers, there would be no religion. Without religion, there would be much less blind faith and self-deception. With less blind faith and self-deception, there would be
much less of a 'religious' basis for atrocities like native/pagan assimulations, witch hunts, crusades or inquisitions. Why do there have to be followers of such self-deceiving blind faiths, indeed.