I am really thinking about investing over $15000 of my savings into Bitcoin. Would this be wise? Is BTC safe and stable at this point and this time?
BTC wouldn't be stable it would always have it's price fluctuate you should decide it on your own see how the price has been and decide if it's a good investment for you or not.
The price could go up or down in the future and you should also be aware of it and don't expect that the price would only go up in the future.