Q - If you as consumers, know about the false markup, would you still prefer to buy from that online store?
I am well aware of this false markup, I do still prefer to buy from that online store (aka amazon) due that it's still cheaper and more convenient than a conventional store (have amazon prime thus things get fairly quickly).
Q - Is there any resentment against that online company?
I would be lying if I said I'm cool with them doing that, however it's not to the point where they would lose my trust because of it. Also it is worth noting that the conventional big chains also use this tactic, and sometimes the price is higher after the discount than the original price haha. What amazes me is how people are so gullible that they will just say, "holy fk 80% discount, now it's only 300 dias ?!?!?!?!?! Gotta buy it before the deals ends
" without realizing that there's something wrong (it's just an example, don't get mad at me).
Q - Would there be a difference in your thoughts and buying behaviour if there was not a monopoly or duopoly? (Either one of two companies dominating the entire market)
My thoughts wouldn't really change with competence in the market, I'll still buy from the cheapest and most convenient source, and that doesn't change with prize changes or these guys doing things differently.