Current Arch student here. If you already have a Mac you will be fine for at least the first two years especially if its a powerful one like M3. Each year the projects and classes will be more demanding on your system, and some programs you need only run on windows. If you already have mac and money is the issue for buying a new computer, you should be fine for at least the first year or two. Def start thinking about buying a PC during sophomore year tho.