Check your clutch safety switch.  Over time the switch wears out/gets dirty, and you get nothing when you hit the starter button.  Just disconnect the switch and jumper the wires in the plug that goes into the switch.  If the jumper corrects the problem, then you have found the culprit.

Check your neutral light.  If the light is not illuminated when the trans is in neutral, the sidestand relay thinks the bike is in gear and the relay won't send current to the engine run switch and starter button.  Sometimes the blue wire breaks loose from the neutral switch inside the primary drive.  If that wire breaks loose, the neutral light won't illuminate.

There are a number of things that can cause this, all of them in the push button to starter chain.

check all of the safeties.
check the push button, a volt meter on the dreaded clutch safety connector.
check the on/off switch, sometimes flipping it on/off a few times will work.
check the kickstand switch, under the seat is a green water proof connector, pull it and you'll get direct access to the kss. ohm meter and push the button a few times.

my bet is the on/off button, I've had that before.

What Verslagen said about checking the safety switches - the clutch safety switch can go "wonky" and prevent the starter process from engaging - try bypassing that switch the same way you have bypassed the sidestand switch (and/or test it with an ohmeter to see that it is working properly).

Also check the wire connectors under the fuel tank to make sure they are tight and free of corrosion.  Those connectors are originally sealed pretty well from the factory - but when folks disconnect them they often disturb the black tape that seals out water.  The rubber cover is originally sealed to the wiring harness at the top/front - but it is impossible to slide the cover back to access the release of the connector with that tape in place.  The tape is often removed and never replaced, and it allows water to get into the top of the connector.  (Always use tape and reseal the cover to the harness when you are putting the bike back together.

The wiring harness from the connectors also turns with the handlebars, and it is not uncommon for a wire to break in the harness near the forks.  The wires to the headlight are the ones that most often break in that area, and it often causes the high/low (or both) lights to stop working.

The next time it fails to start - try turning the handlebars left/right and see if that makes any difference.

DragBikeMike has had one or two clutch safety switches go bad for him - so it is a part that has failed for folks.  The side stand switches are also know to go bad.

I have removed both of those safety switches from my bike - I just don't want to be riding in some remote area and have to troubleshoot why my bike won't start (in fact - I have removed the entire decompression system and I have a manual decompression release).

For me, I don't see the removal of the safety switches as a potential hazard of significant merit.  I started riding long before those were used on motorcycles, and I have developed a routine that involves me getting on the bike and folding up the kickstand before I even reach for the key.  I also look for the neutral light as soon as I turn on the key, and my hand is on the clutch before I hit the starter button....it is just a habit I have developed after riding for more than 60 years!!!!