Well what I mean is that unless you really need everything on your computer to run at SSD speeds (you probably won't) you should get a smaller one now, and save the money, and then later you can get a bigger/faster one as needs demand. You're not losing anything, but you have everything to gain: 1) by the time you need to add more storage drive capacities/speeds will improve, 2) there may be sales that you can take advantage of (I was able to get a 128GB M4 drive for $90 in one sale), and 3) it's easy and unintrusive to install new drives.
If you were in a laptop or something small it would be a different matter, but you have a full-sized motherboard and case, so you can add tons of additional drives as needed. On my own system I've added many drives over the years; at the moment I've got 8 different disk/ssd drives on this system.
It's good to think in the long term like you are, but remember that only slower-changing components last that long ((CPUs, motherboards, RAM, video cards, etc.). Storage drives are one of those things that don't last 5-years at a time because they improve so often. That 512GB is a lot of SSD space -- space that probably doesn't all need to be at SSD speeds, or will all be used. You could get away with a smaller one, say 256GB or even 128GB, and then later if you need more space for games or something, buy another when they're even cheaper. For media that doesn't need SSD speeds you could even get a large hard-drive based drive.
Overall, you'd be saving money that you could spend later to improve your system again with better hardware than you could afford now. If I had purchased 512GB of SSD space when I first got my old 80GB Intel it would've cost more than my entire computer. Waiting until I needed that extra space, I was able to get some other SSDs over the years for cheap and add them in as needed. I didn't suffer from doing that because I wasn't using that space anyway even for a main drive because most of my data is just being stored, not accessed. My SSDs are for my Windows system drive and programs (80GB works fine), and another SSD for games that I actively play. Even if I had 512GB I probably wouldn't have been using that fast storage very optimally for stuff I rarely access -- stuff that should go on a regular HDD.
So think it over. You can save $175 now and get something better later. It's the name of the game in computer parts.
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