My Kindle archives say I've accumulated at least 2000 official publisher-promo freebies via Amazon alone. I estimate that I've read maybe 1% of my variously-acquired freebies at most, although I did go on to buy several more works by new-to-me authors as a result of reading the offered freebies.
I have yet to pay so much as $10 for a single e-book.
I have also spent
upwards of $700 on e-books in the past year alone, and I'd estimate that e-books I bought and paid for myself made up at least 1/3rd of my
total books read last year, and this year thus far they've been well over 3/4ths.
But that's kind of due to seasonal rain making the Kindle-in-a-baggie the only practical way to read while I wait for the bus, rather than any innate preference or switchover to primary e-reading.
There are plenty of good and interesting e-books regularly available at or below my preferred non-free price point. While it would be nice if some the higher priced ones I'd like to have became so (either via special discount or re-pricing), I don't feel much in the way of urgency or compulsion to buy higher-priced e-books to own.
Of course, I have a readily-accessible generally well-stocked library system to draw upon and have no disabling difficulties handling paper formats, which may make a difference in what other people are willing to pay for books they want to read.
As for gift cards, I have some small gift card amounts padding my account because most places charge in USD, so an accidental purchase would mean I lose out on the currency conversion if I end up getting a refund. I've hit the wrong button for sampling at Amazon more than once and I'm determined that if it happens again, at least I won't be out extra money due to their annoying no-confirmation 1-click.