It does sound like a bad connection or faulty starter switch, it only needs a loose connection on the starter cable to be an intermittent fault, it’s annoying but it’s a process of elimination, disconnect the battery and one by one undo each cable connection, clean and reassemble as you go, if the fault reoccurs put a test light on the battery side of the starter switch to check power to the switch, if there’s power put the test light on the starter side and get some one to press the starter switch ( obviously mind fingers and hands in case it engages) if you have power the switch is ok and the fault is most likely the starter.