It's not just time too. Some of us don't have the space or want to invest in the tools required to build from scratch. If there's a nice ARF I tend to purchase that kit rather than build a kit. I would rather spend my free time on flying than building. I only have a limited amount of time free each week/month to fly so building would eat up that time. My choice is to spend more time flying and less building because that's what I like to do with my free time.

I also prefer to work more, make money and spend it on ARFs. Maybe when I decide to retire or cut back on my work hours I will find more time to build. ARFs have their place for many RC people. Give me more flight time any day!