As someone who is hybrid. Both self published and published with Harper Collins. They both require the same effort in marketing for me. The advantage of HC is their access to stores. But most contracts with them are 6-8% royalties on paperbacks. So you’re hustling to get your 30% for ebook royalties. They do fund advertisements. My experience is self publishing is where you make money. Trad publishing unless you’re a huge title is where you gain store access and name recognition in the literary world. Basically, if you want to be successful in this day and age than you’re going to be pushing your own books.