Are there any alternatives?

Several, all of which are better. The RTX 3050 is the most direct competitor, and it’s far better. You can go back several generations and still get comparable performance, with even the RX 5500 XT coming close to the RX 6500 XT.

　　

How long will it last?

Not long. The RX 6500 XT already has severe bottlenecks in games that are a few years old, and those will only become more exaggerated as time goes on.

　　

Should you buy it?

No.