Update to AMD Ryzen 5700x3d

A little back story, I built my first PC in early 2023 with a budget of 1000€. At the time I opted for AM4 instead of AM5. Here are some of my specs:

Asus ROG Strix B550-F Gaming

AMD Ryzen 7 5700x

Corsair Vengeance LPX DDR4 2x16GB 3200MHz

MSI MPG 750W, 80+ Gold PSU

Asus Radeon RX 6750XT 12 GB Dual OC

However, the graphic card had very loud coil whine so I returned it. While deciding on what graphic card to get instead, I found a used Asus TUF 3090 OC for around 700€ and bought that instead.

From what I've read 750W PSU is sort of the bare minimum for a 3090, but I haven't had any issues so far.

Since I'm on AM4 I now feel it might be a good idea to upgrade to an AMD Ryzen 5700x3d while it is still possible to get your hands on, to make my computer last as long as possible. However that means I also need to buy a new PSU right?

Is there any point in trying to sell the CPU and PSU after upgrading, or are these parts not worth much used?

Any recommendations for a somewhat beginner on all this would be much appreciated.