What would constitute a big enough cause, for you to boycott?

People like them. The computer you're typing on is inessential to life. I would bet that 90% of the money spent in the US is on things that are not essential to life. If you're going to stop using everything that is non-essential to life then there isn't going to be a lot left, in fact you won't see this answer because you'll be off your computer. The barrier to turning it off is that people like it. No one is forced to drink it.