Stories abound of how items like eggs sold for $8 an egg (about three months wages for an average American at the time) during the California gold rush. Certainly fortunes were made during the California gold rush but how many fortunes were founded on mining gold versus selling general supplies at inflated rates? I suspect far more of the latter than the former.
I mean, it kind of goes without saying I think. San Francisco became a major city because of the gold rush, going from less than 1000 residents in 1846 to 50,000 by 1855. ALL that was gold-rush related in some way.
Several extant companies were founded to supply goods or services during the gold rush - Levi Strauss & Co and Wells Fargo are probably the largest two you’d know of. Others had their initial capital stake generated as a result of the gold rush, even if the companies were founded later and elsewhere - Philip Armour made the capital that founded Armour meat packing in the gold rush, and so did John Studebaker.
I’m pretty sure that’s well-established. The people who got really wealthy weren’t the prospectors, it was the merchants, and later the people who bought up all the claims, like George Hearst.
You can spend a day selling a hundred shovels to a hundred men, and make money, or you can spend the day digging, and maybe make nothing. Even if 99 out of the hundred men make nothing, the shovel salesman still makes money.
Leland Stanford by himself probably made more money than all the prospectors combined.
Or you could manufacture shovels and make a fortune (or increase your fortune, since the Ames brothers were already a growing business).
Many of those who made such fortunes during the Gold Rush made more fortunes during construction of the transcontinental railroad.
Steamship businesses were big winners early on as most of the prospectors traveled to California by sea and most of their supplies were sent that way.
Hearst? Any relation to William Randolph?
Indeed. Mostly remembered as the bad guy in Deadwood. 
They were, however, often struggling to find a crew willing to sail the ship back - in many cases, sailors who came to California on a ship deserted to mine for gold themselves.
Were there any miners who made a fortune strictly off mining gold? All of the names associated with making their fortune in the gold rush – Strauss, Stanford, Hearst, etc. – did so through mercantile means. John Sutter himself ended up bankrupt.
Except many ships were simply abandoned by their crews and left rotting.
Yep.
I can’t think of many fortunes, but a few sane souls went home with their winnings, or bought land in California. There were a couple of original families in Santa Cruz – one was Spanish – who bought land and built their windfall into substantial family businesses. Probably were the kind of people who would have been successful anyway.
I’m reading In The Heart Of The Sea, the story that inspired Moby Dick. The closing chapter mentions that many men abandoned whaling and sailed their ships to California to join the gold rush. One source says that some 600 men and 14 ships sailed from Nantucket alone. From the Nantucket Historical Association:
In 1848, gold was discovered at Sutter’s Mill in Coloma, California. “Gold Fever” swept the county upon the news of the discovery as men rushed to cash in on the find. No fewer than fourteen vessels sailed from Nantucket to San Francisco that year, loaded with passengers and crews eager to seek their fortunes. By January 1850, 650 Nantucketers—a quarter of the voting population—had headed west. They were joined over the next few years by hundreds more islanders who might otherwise have worked in the island’s or New Bedford’s whale fisheries…
Oh, you’re looking for those who profited by inflated prices. Here’s one:
Assuming most of the ships were a few decades old, ship owners were probably upgrading to steam vessels anyway.
Entirely possible. A lot of the steamships in that era were either converted or built just as sailing ships had been, except with the addition of steam engine and paddle wheel. A few had screw propellors, but all of them maintained sails and rigging in case the steam engine failed.
Seems much the same as Howard Hughes, who made a fortune out of oil without AFAIK drilling a single well.
which is why SF is built on landfill
Well, a tiny part of it on the waterfront anyway.