Former (90s) professional windsurfer here, now kitefoiling exclusively.
I was perhaps a foolhardy young chap, and maybe lucky, but I did long-distance ocean solo missions all the time. A couple of times it was well after dark when I made it home, and a few times I had to self-rescue with broken gear, but I never needed rescuing. Again, maybe lucky, but I'm sure there was a very different sense of self reliance back then. From the depths of winter and Melbourne Covid lockdown I'll offer some glory-days yarns, for what they're worth:
My adolescence in the 80s had consisted of windsurfing solo on the Manning River pretty much every day after school, and dealing with whatever happened. This was a good grounding in self reliance. Once, several km upwind of home in a black nor-easter, I snapped a boom extension. I sailed carefully to the nearest shore with hands spread wide on the good side of the boom, pulled up on the mangroves, and began searching. I found a length of inch and a half ag-pipe (cattle country), managed to cut off a few feet using the rough edge of a concrete trough, and used this to sleeve the boom extension, wedged in place with some sticks, and, as I recall, sailed full speed back home in the back straps with no issue. (I would have been 15, on a Cobra 380 race, Gaastra 7.0 racefoil pro, and a crappy old alloy boom)
I used to pore over Sailwind Quarterly, Freesail, and whatever US mags I could get, and there were lots of good self-rescue articles in them that helped me with general principles and specific solutions.
Most challenging self-rescue was off Cervantes at the slalom comp in 93. Sailing back upwind around the slalom course, my mast broke below the boom as I leaned into my outside gybe. There was a rescue boat for the comp, but they didn't see me. Wind 25-30 knots, cross offshore, I'm losing ground quickly. I'm on a 5.6 race sail on a small slalom board, maybe 55litres. If I recall correctly, this is what got me back in. Backed the downhaul off, released the clamp on the boom but left the rope fastened so it could slide up the mast. Worked the bottom of the luff sleeve up over the break in the mast. Sitting astride the board, fully released the downhaul, pulled the mast off the extension and threw the bottom bit (maybe 70-80cm) away (sorry planet) whilst holding the rest of the rig. Pulled the extension off the uni, and somehow managed to jam the extension up the broken bit of mast. Downhauled very loosely, with plenty of slack. Worked my way to the mast tip and pulled a couple of feet of luff sleeve over the top of the mast. On the way back down the mast, I tightened the boom head to a raised position. I then put a touch more downhaul on, and put the extension back on the uni. Very gingerly waterstarted with the sail somehow not ripping, and grovelled in on a broad reach. Probably was 15-20 minutes to jury rig and another 20 to get back in, and the maybe an hour's walk back up the beach.
Once, at sunset, off Sprecklesville, I had a mast break maybe 1.5 km offshore. There was no jury rig option this time. Just derigged, rolled everything up as tight as possible and tied it up with downhaul and outhaul and, balancing awkwardly with the crap along the middle of the board, paddled back in downwind to Kanaha (straight downwind, and where I'd started from). Well dark by the time the paddling began. Kicked the fin at one point (very sharp trailing edge) and thought I might have drawn blood, just to add some excitement a few days after a tiger shark had given a local surfer's leg a thorough makeover. This was on 270x54 cm slalom board in 20ish knots.
I've self rescued and jury rigged kitesurfing maybe a dozen times in as many years of the sport. It is a perennial theme among kiting commentariat how few kiters can do basic self rescues in even the most commonly encountered issues (wind drops/ broken line/burst leading edge) ... but I digress ...
I'd emphasize the rule of never ride anywhere from where you wouldn't be confident of being able to swim in. Other questions - How calm can you remain when things go wrong? How fit are you? How good an open-water swimmer? Do you have basic plans for common breakages? I'm not against radios and epirbs, but you'll still need to keep your head and survive for a while before help arrives (assuming it does), so there's no substitute for preparedness on all fronts.
There are few feelings like offshore sailing in gnarly conditions. For some of us it is a calling, and only a fool would refuse it. As T. S. Eliot put it:
Old men ought to be explorers
Here or there does not matter
We must be still and still moving
Into another intensity
For a further union, a deeper communion
Through the dark cold and the empty desolation,
The wave cry, the wind cry, the vast waters
Of the petrel and the porpoise. In my end is my beginning.