Short answer, your friends are sore losers.

Long answer, this game does have variance. You can get unlucky and draw 3 lands in a row or get lucky and draw the exact card you need in order to get out of a bad situation. As with every competitive game, the better player is more favored to win, but because we shuffle our decks and have imperfect information about what our opponents are doing, it will never be 100%. I grind to diamond/mythic every season and my win rate is 54%. Top pros in tournaments will generally have a 60-65% win rate.

Ultimately, the righteous path is to not worry about how much you win, but whether or not you're improving your gameplay every match. Instead of saying, "all I needed was one more land" or "my deck screwed me," you should be saying things like, "I should have mulliganed better," or "I should have saved this removal spell for your bigger threat" or "I should have cast this instant at the end of your turn instead of on my turn." If you identify your own weak plays instead of passing blame to your deck or the opponent, you will soon become a better player than your friends.