The idea is a good one.
Getting people to squirrel away a few bucks worth of BTC each week in a piggy bank format is cool.
Currently, the weak link is your execution. Get that right and I suspect you will have a vibrant market.
Embrace the security issues and explore how you can use these comments and ideas as source material to educate future piggy customers. This btw is key. As a provider it is your responsibility to educate your customers. Get it right and they'll be back for your next offering ....
There's a really cool opportunity here, don't blow it with cheap short cuts or lazy thinking
The audience may be critical, but they do love a good idea well executed and will pay for that too
Viz