He needs to thank his lucky stars he is here and starts in one of the biggest clubs in the world that plays best football.
Not a single lucky star was involved. He came when your biggest club was in shambles, completely humiliated by Bayern and on your way to EL level. Your bosses jumped at the occasion for a marketing effect of the Bayern poster boy coming to the club despite all that, to create the impression of the club with irresistible air of legend and whatever bs was needed at the time. Both Lewandowski and his snake agent knew it, and the value of it, hence the insane contract, that you're all so clueless when crying about. It's you who are lucky he saw a challenge and opportunity to be a hero in all of this, went for the deal, and you had your little win.