Also this isn't even considering that the overbudget and long build times only apply to western reactors. Korea and China builds them pretty fast (avg 5-6 years) without cost overruns and in the past Japan built their fleet with an average of 4 years and sometimes even under budget. It can definitely be cheap as scale of economies do apply to them when you regularly build them along with having an active supply chain and experience for them due to them being built regularly.

Also for the safety issue the newer gen4 designs are passively safe where a meltdown is physically impossible as it can self regulate cooling without any human interaction. SMRs also are designed like these since they're small enough that dealing with the decay heat isn't as hard compared to large reactors.