The negative road safety outcomes of high speed are evident at an aggregate level. At the level of the individual driver, the risk of an accident is very small; at higher speeds the risk is higher, but still very small. Hence, an individual driver will hardly ever experience the safety consequences of excess speed. More or less the same applies for the environmental effects of speeding. These are also noticeable at an aggregate level, but hardly at the individual level (possibly with the exception of fuel consumption).
Contrary to the disadvantages, the advantages of higher speeds are experienced at the individual level. Individual advantages include just reaching traffic lights while still green, (subjectively) shorter journey times, thrill and enjoyment of speed or speeding.
This contradiction between societal and individual consequences makes persuading drivers of the value of speed management a difficult mission.