What's a good thesis statement for a comparing and contrasting essay on some being courageous compared to them being wreckless.
Not going to give you a thesis, but in general, assuming this is the opening thesis for your introductory paragraph you need to have certain points that you're attempting to argue and then from there come up with a thesis.
So, try coming up with some general points that you wish to argue about throughout the essay, and then come up with a thesis from there.
You may get more help if a mod moves this to the Writing Discussion forum.

First of all, *reckless, that will help if you're sending this to a school.
Nobody's going to just hand you a thesis statement...and if they don't know the content of your paper it's not going to be a very good one anyway.
Come up with some examples (either from your life or history, whatever they're asking for), and ask yourself questions about them. Think about what makes one action an example of recklessness and another an example of courage. Is there a grey area? What do the 'courageous' acts have in common? Get a little more abstract--is success or failure of the action important? Is something seen as reckless because it's going against some traditional view? Eventually you'll find an angle that interests you and start to form an opinion--THEN you can base your thesis statement on that interpretation.
It's like writing a research paper--you don't think of an argument and then do your research afterwards to back it up. You research and think about the topic first, and that's how you form your argument which will be the starting point for more research, etc.