$15000 is a lot of money and I think there are things that needs to be considered before investing. Investing in cryptocurrency is a high risk investment which means its volatility rate is high compared to other investment vehicle such as stock market. Bitcoin price can generally increase in value as well as it can decrease in value at a very fast pace, thus there is a greater chance of losing especially when you are illiterate in cryptocurrency trading. You can observe bitcoin price index in real time by visiting
Bitcoin Price Index just to make you aware that it is not a stable investment.
If I were you, I think you must consider first having an emergency fund before investing in
BTC to give you a peace of mind and to keep yourself afloat from unfortunate fortuitious events. After setting up your emergency funds, get out of your comfort zone and learn as much as you can about trading from the internet or in this forum. Spend some time before investing.
You might also consider reading this thread for you to be able to store your earnings if ever you have started investing, keep in mind that you should also prioritize your
BTC stash security.
[General] Bitcoin Wallets - Which, what, why? Is BTC safe
Safe from what? If you are pertaining to the security of your funds, then you should consider reading the link above. But for peoples' choice, having a hardware wallet would be the best solution to secure your funds because you are holding your own private key which grants you a full control to your crpyto.
If you are referring to the algorithm of blockchain where bitcoin transactions are being held, it is totally safe because every transaction are shared in a public ledger where anyone can see and validate that the transaction is true. AFAIK, blockchain cannot be tampered because each block has a unique cryptographic fingerprint and follows a consensus protocol.
It is also important to keep in mind that bitcoin is the first network - centric, protocol based form of money. It means that you can have a full authority in making transactions without the intervention of middlemen or institutions. In simpler terms it is very much secure while maintaining your anonymity.
Anyways, DYOR as well since there are some points that I missed for sure.