It can vary, but it's not uncommon for a switch to fail from softening plastic around the electrical contact. Sometimes this plastic can deform enough that the contact stops conducting current. One potential cause recently can be a headlamp with higher wattage than stock.
The switches can also collect dirt(from years of use), once the dirt starts to collect it will interfere with the switch contacts conducting current, and you then end up with the same situation as above......softened and deformed plastic.
Once the switch is fresh, the relays will control/switch the lamp current, so that the bar selector switch will only have the current load of the relay coil.
Re the original question, he really hasn't said yet if it is just the indicator that isn't working or if the headlamp is also not working.