"G. Underselling the product to grab market share while subsidizing the losses with the profits from other markets (or other products)"
um... and in the period of underselling: THE CONSUMERS WIN
it is called... oh yeah step A. they'll raise their prices again, but as long as the barriers of entry are low, more competition will arise.
"H. Being Bigger, part 1: economies of scale"
being bigger, ALONE, does not guarantee success. you need some of my prior steps. be more specific with economies of scale
"Being Bigger, part 2: leveraging their size to bully the supply chain"
and HOW do they bully? lower prices to put others out of business: HELPING THE CONSUMER? merging companies: profitable for the smaller businesses than not.
An actual businessman know what bullying is. Filing court cases harassing smaller businesses, demanding more regulation that they can afford to take care of in bulk costs, cooperation with local gov't to make barriers of entry, illegal manipulation of several levels of the market.
"J. Making their size the product (i.e. brand recognition)"
brand recognition works three ways: you're remembered for a bad product, you're remembered for a good product, you're just familiar. the first two are FAIR, and the third only applies to the lazy consumer.
"Someone who isn't pulling shit off the top of their head could probably double down on this."
yeah, there are a shit ton of ways people with money can stay rich, but the ones you listed there (Except H, which I THINK might be something ia free with -margin of reinvestment-) i dispute.
nonetheless, the number one way is gov't collusion.