Well I don't believe Google sells users info, but I also don't think there is enough transparency with companies, Google included, as far as what they do with out information. I use a lot of Google services since they are useful and they take security seriously.
Unfortunately a lot of more seemingly innocent companies do like to sell your information such as when you sign up for the savings card at the grocery store, that magazine subscription you may have. Those companies make a fortune off your info.
Yeah Google does have some of the best services. I've used a lot of different calendars, for desktop, cellphone, cloud etc. And no one comes close to creating something that competes to a busy calendar. So I understand how Google having access to how it's users are actually using their software allows them to creates features that we want and great improvements. But yeah more transparency would be nice like, we use X algorithm in Gmail to help Y feature. I don't know, but yeah more information to help us understand what they are doing with it would be nice.
And I agree that Google's security is top notch! No one can accuse them of being lax in that area. And they're not going anywhere anytime soon or in the future so they have longevity as well.
I think as a society we have moved into a space where we didn't think about the personal information part because of the convenient service we recieved for "just" signing up. But I think this is changing with all the data base leaks, hacks, or systems being manipulated for users personal information.
The average user probably only sees the high profile data thefts that are on the news and likely only becomes conscious of the problem for a short while after. They will just rationalize that "I'm not that important, so no one will want my info" and they will just shrug it off. Seen it happen.