So this will be your last achievement, unless you chose to skip over something to prove me wrong. Opening packs gives xp, customers buying items and playing at tables gives xp. I would personally use your second shop and fill it to the brim with card tables. You can also ALT + Tab while holding left click while opening a pack to open packs without holding down the button. Additionally in the settings you can turn pack speed to max and have it auto skip new cards (not like theres gonna be many) Good luck!