You are doing well enough to save to do your own project to do later.. Eventually this company will move on from your work, even though it seems impossible now, they are quietly trying to figure out a way to do so. When they do, just be keeping your expenses low now and low in the future so you are not dependent upon a job. I have made the mistake of becoming "invaluable" and every time the company management works to find a way to replace me because they want to show they are in charge and are not dependent upon any one single person even if it is not in their best interest to do so.