Squeamish from the start about pursuing profits in one of the darker corners of finance, established firms this year slowed their already halting efforts to make a business out of Bitcoin mania. Take Goldman Sachs Group Inc., which sought to position itself at the cutting edge of digital assets that skeptics see mainly as a domain of day traders and anarchists. Many in the industry now say it was quixotic to have expected last year’s frenzy to translate into a Wall Street crypto offering.