That's because the three survival options Nishimura suggested would change the minimalist site's look and operations. The first method would halve traffic cost by limiting image upload sizes, using slower servers and shrinking the site. The second would flood the site with pop up and self-described "malicious" ads, while the third would push more users to sign up for paid 4chan passes.
Since its inception in 2002, 4chan's anonymous, no-limits conversations gained it a notorious reputation that definitely scared away advertising revenue. In 2007, it was banned from Google's ad network AdSense for violating its appropriate content policy. It had kept afloat during its early years thanks to ads from anime purveyor J-List, according to Mashable, but that agreement ceased in 2012. It doesn't help that its community uses adblockers far above the normal rate.
But even before internet advertising got as bad as it is today, 4chan's founder Christopher "moot" Poole was charging server fees to his credit card to keep the site alive. Then he stepped down as site-wide moderator in January 2015 and sold it to Nishimura, who created its Japanese inspiration 2chan. By March 2016, Poole was a Google employee, and his site continued its struggle to stay alive with lone banner ads.
For all the depraved conversations occurring on its more feral boards like /b/ and /pol/, 4chan has maintained a sense of visual decorum, if that's what you call refusing the more obnoxious and ubiquitous ads other media sites allow. It has notably limped on with only lone banner ads at the top.
While Poole prohibited anything but non-invasive ads that wouldn't ruin the user experience, as he described in a 2009 Washington Post profile, today's 4chan runs few ads so they won't tax what little server bandwidth the site, well, can't afford anyway. If more ad revenue doesn't materialize and nobody steps up to bail it out, 4chan could force itself into a cash-saving compromise that changes everything that makes it...whatever it is.