Chapters in my thriller before the main threat comes in

Will this drive readers away?

Yes and no. It all depends on your implementation, and you have to thread a needle.

At the very start of your story the reader doesn't know or care for your characters yet. It's only logical to use the first few chapters to accomplish this goal. What's your character's job? In what sort of place does the character live, and with whom? Family? Alone? With roommates? What's the character's natural response to seeing a kitten stuck in a tree?

This is what fantasy writers call the 'normal world.' However, the 'normal world' is a part of all genres. The only distinction is length. If I write a story about a humble kwama egg farmer of House Hlaalu from Balmora, I'd need to explain all three of those things to the reader early on and the opening chapters would naturally be longer. Books set in the real world can be shorter in that regard because the real world is already familiar.

Though it's necessary to have an introduction, you're completely right in that the opening chapters should under no circumstance be boring. If you want an agent to delete your manuscript after reading one sentence, start the story with the MC waking up and going through a morning routine.

Action and intrigue do indeed build excitement, but it's possible to go wrong. Every sentence you write should do one of three things: advance the plot, show something new about a character's personality, or relay crucial information necessary to understand the story. Anything else is filler, and readers will recognize it as such.

If your MC is a cop and the first scene shows him chasing and failing to catch a jewel thief, that jewel thief better show up later again in the story. Alternatively, if the jewel thief is entirely unrelated to the larger plot, the scene could be used to show the cop is out of shape, cares more about free donut privileges than doing his job, and thinks solving crimes is beneath his station. If you have a similar scene to this elsewhere in the opening, you can safely delete it.

I suggest to look at your early scenes with a critical eye. Do they serve one of the three purposes? If not, can they be edited so they do?

Don't write spectacle for its own sake. Firework shows are pretty spectacular, but pretty much nobody who records a show watches it back later.

If this is a bad idea by itself could a prologue with future events make it better?

It makes the problem worse. If I read an awesome prologue and the next chapters are filler, I'm going to be disappointed and stop reading before the story catches up with the promised events.