Why some people don't believe in UFO sightings?

when i was 7 years old i remember i see a soucers flying, about 17 inches wide, green color. light is rotating counter clockwise and some light rotating other way around,i remember i see the light red,yellow,blue,white,ect.they are rotating and a wierd sound.its very near to me its like a toy but its not. wierd but i belive.