The main advantage of keeping accelerating when you're at >90% of the speed of light is that it means you arrive faster in subjective time. You could take 160 years to get there and use ten times less fuel (or thereabouts), but the subjective travel time would go up by decades.

Not that smarter when they forget you're running out of gas by the Oort cloud. Gotta spread christianism capitalism there and build a petrol station before we go further.

Earth’s gravity being what it is a blessing cause it means we can do interstellar travel faster.