The crashes are almost certainly due to memory issues. While your machine sounds good for general purpose work, you can easily rent machines with more RAM from any of the cloud providers or get access for free if you have an academic affiliation.
If your goal is 3D printing, then upsampling should help you preserve details and smoothness that would otherwise be lost during segmentation.
If your goal is mainly to visualize the data, then using volume rendering is often a more effective solution. You may also want to combine segmentation and volume rendering using the Colorize Volume module in the Sandbox extension.