Why do meteoroids usually disintergate rather than fall to eartn?

Answer 1

Because, they are to small.

Answer 2

Meteoroids often disintegrate in Earth's atmosphere due to the intense heat generated by air friction during entry. This process causes the outer layers of the meteoroid to vaporize and break apart, resulting in the formation of a bright streak of light known as a meteor or shooting star. Only the largest and most robust meteoroids are able to survive the intense heat and make it to the Earth's surface as meteorites.