First movers have an advantage when they can raise entry barriers (economies of scale, network effects, switching costs).
However, fast followers or late movers have some important advantages, and if the early movers don't have significant barriers they can pull the rug from under them if they have a superior product or better business model.
http://staffweb.ncnu.edu.tw/clhung/MOT/Mohr02.ppt (slide 19 and on)
First movers have an advantage when they can raise entry barriers (economies of scale, network effects, switching costs).
However, fast followers or late movers have some important advantages, and if the early movers don't have significant barriers they can pull the rug from under them if they have a superior product or better business model.