Good team + great managers+ cheating+ luck
Ridiculous standards.
The way they treat players and managers might be hard to stomach for some, but it works. Its a club obsessed with success and it shows.
They are different. And it works for them.
These. The first quote, it's applied to any club / national team, it's not exclusive for Real Madrid. You don't win elite elimination tournaments like Champions League, Euros or World Cup without having luck in the right moments, plus a bit of dodgery -knowing how to compete, which is very different to how well you play, no matter the style you play, it's what makes a difference between "adult" and "kid" footballers-.
The second quote, and I'd like to expand it as a spanish to show my point of how in the biggest part of the globe, but more concretely by the brits in an exaggerated way, don't understand why the "spanish whistling and booing thing" at all, they don't simply get it, it's a lack of complete awareness about it. You can approve it or not, but it's the way the spanish have to ask "guts" to the players and courage: it's a way the spanish have to ask respect for them, for the public, to the players. Public goes first, players next. "They" are the club, the public is. The players can be changed, "they are really well paid to stand for whatever the public asks" as the common supporter here says. They don't do it because they like to moan about each little thing, but because they demand the best in each concrete case, not only in the bigger clubs, but also in the "middle ones", some of them historical. If Valencia or Sevilla don't enter the Champions League, it's a terrible season. If Athletic de Bilbao, Villarreal, Celta, etc etc doesn't enter into Europa League or doen't even show a "fight" for it, the coach will be sacked most probably, whether at some point of the same season or at the end of it. It's a matter of ridiculous standards that in lots of cases crash really interesting mid-term projects on paper in their first season, but hey, it works in lots of cases.
Also, you may hate him or love him, but Florentino Pérez has been brilliant in his second run at the front of the club. Yeah, they almot didn't win La Liga all these years, but who cares, all that matters to Real Madrid fans is winning the Champions League, because that also ruins / nullify the season of Barça whatever they do. Champions League is what makes you reach a "global" prestige / publicizing / money / players / social media consumers.