Yes and no. Big players will react and offer special deals to people in an area to keep them and lock them in for another year or more if they perceive your ISP

Yes and no. Big players will react and offer special deals to people in an area to keep them and lock them in for another year or more if they perceive your ISP as a threat, but if you offer reliable service and good speed and good support, you can eat their lunch. The problem is that to be competitive you might be looking at years to break even on investment depending on what you offer and where, and how you deliver it. Running fiber on poles to deliver 1gig or 10gig? The buildout is expensive, you have to target dense areas or buildings with lots of units, and even then it's a lot of up-front money and it will be a while before you're out of the red even with a good takeup rate.