No not all paintball markers are electric. For instance the Tippman 98', and 98'custom, one of the most reliable and trustworthy guns on the market, are not electric. However buying an electric marker does grant you some benefits. Serious paintballers use electric markers because they allow they to select and customise a mode of fire that best suits them. Some electric markers also have an "eye" which prevents the gun from firing unless a paintball is completely loaded into the chamber, this saves from the firing with no paintball in the chamber or when a paintball is not fully in the chamber. Electric hoppers also are used to more quickly feed balls into the chamber on higer end guns.