Turkey has had several coups. So I'd look at what happened after the previous ones.

None of them bore any resemblance to Erdogan. All the previous ones were the army emerging from its barracks, deposing democratically elected and popular governments they thought too Islamic/not secular enough and returning to their barracks. The current political situation is a result of the increasing democratisation that the EU encouraged. Erdogan would never have been tolerated before.

In this case it's especially ironic. The Army regarded themselves as the guardians of Turkey's secular democracy - even if that meant acting anti-democratically. This is of course a problematic position.

Now Erdogan - as a result of genuine democratic support- has gained enough power to make his move and has resolved to dismantle democracy and weaken certain factions in the Army to protect himself against any similar future coups.

Actually the kemalist factions in the army and police were the guardians of secularism (not quite a secular democracy but close) until Erdogan took care of them.

Well... It was properly executed and it has succeeded in giving Erdogan more power.

I asked a Turkish friend if she thought the coup being a false flag operation was an outlandish conspiracy theory and she strongly disagreed.

Of course that means nothing other than "one specific liberal ex-pat Turk believe X was plausible" but it's one more data point.

Coup was probably real but failed and Erdogan exploited it for his own ends. He's a very able and dangerous politician.