Can i die from serum sickness if i ignore it?

Yes: Serum sickness can lead to organ damage and vascular collapse if the offending agent is not stopped. Normally however it is a self-limited syndrome which resolves after the offending agent is removed.

Rare but possible: The greatest danger is kidney injury resulting in acute renal failure. This is more likely if you already have compromised kidneys from pre existing conditions. You might need dialysis for a few weeks until your kidneys recover. The key in serum sickness is monitoring - adding therapy when needed until the problem resolves.