This is a basic transform of your element into a directive. There is no real advantage of doing it but it does what you want:
> demo fiddle
View
<div ng-controller="MyCtrl">
<my-directive></my-directive>
</div>
AngularJS application
var myApp = angular.module('myApp',[]);
myApp.controller('MyCtrl', function ($scope) {});
myApp.directive('myDirective', function () {
return {
restrict: 'E',
replace: true,
template: `<md-button class="md-cornered" ng-disabled="0>=gains" ng-click="buyTaxi()">Buy a Taxi</md-button>`,
link: function (scope, element, attrs) {
scope.gains = 1;
scope.buyTaxi = function () {
console.log('Buy me a nice taxi!');
}
}
}
});