Ayup, why else would you think it is getting hot? even cars made from the factory have a separate switch for the fog lights, at least my 86 Astro van and IROC both did. the switch is rated for so much juice running through them, when you start adding high intensity bulbs to a switch made for say 10Watts of juice flow and add another light to that same switch that adds another 10 watts of juice flow it may not last very long.
Technology is great when it works,
and one big pain in the ass when it doesn't
Detroit iron rules all the rest are just toys.