I bought of pair of real, honest to goodness birkenstock sandals. They were stupid expensive compared to the shoes I normally buy.
.....now I almost never wear any other shoe. They fit, they're comfortable, the straps dont cut into my feet now that they're broken in, and I can take them to the store to get resoled for way cheaper than if I had continued my pattern of buying cheap sandals and running them into the ground every few months.
Just wear them. The leather softens from use. If they're dry and stiff, put some leather conditioner on the underside. Maybe you have them too tight. And maybe they're just not for you.