Additional Study Information: The purpose of this study is to compare the usual treatment alone to using venetoclax plus the usual treatment. The addition of venetoclax to the usual treatment could shrink the cancer. But, it could also cause side effects. This study will help the study doctors find out if this different approach is better than the usual approach. To decide if it is better, the study doctors will be looking to see if the drug combination of venetoclax with ibrutinib and rituximab shrinks and prevents the return of Waldenstrm's Macroglobulinemia/Lymphoplasmacytic Lymphoma compared to the usual approach.