Theres different types of invasive (with a tube in your trachea through your nose or mouth) ventilation: CPAP where the person is breathing themselves but the ventilator maintains a pressure so that the lungs arent able to deflate fully, making it easier to take an in breath;
BIPAP where the ventilator breaths for the patient by forcing air into the lungs then letting them deflate (not comlletely) then repeating;
And oscillation, where the ventilator keeps the lungs open and "vibrate" them at a fast rate rather than take proper breaths.
In addition to ventilation itself, if you are being ventilated you probably have: sedation (the "induced coma") possibly drugs paralyzing you, a central line to give IV drugs, an arterial line to monitor blood pressure (and blood thinning infusion to keep it patent), a nasogastric tube, a catheter, depending on the reason for intubation you might have a drain.
With the ventilation runs the risk of further chest infection (ventilator acquired pneumonia), muscle wastage and pressure ulcers amongst other things.
Ventilating a patient is not a decision taken lightly. However it is life saving treatment and the medical staff do amazing things to keep people alive every day. For kids at least ventilation is normally pretty short term (days rather than weeks) on average. I would take ventilation if I needed it without a second thought assuming I was likely to survive whatever landed me in ICU. I would not have supported it for my elderly nan before she died.
Theres lots of medical procedures that are frightening of you look at the specifics of what's involved in fairness.