However, there's a massive difference between good marketing and deceptive/illegal marketing.
Apple does great marketing. Grifters, scammers and spammers do deceptive marketing.
Second, education is not a niche. Education is a sector, one of the largest in the world. Primary school teachers are a market, and bingo cards is a niche.
Technology is a sector, Web developers are a market and version control is a niche.
Boxing yourself into a niche that's too small with a product that's not particularly attractive makes marketing much more difficult than it needs to be.