Here is what they told us themselves, in their own words In January 2020, when the couple first made their public announcement on their website.
They definitely weren’t suggesting they were leaving their Royal roles. Rather, they announced that they had "made the choice to transition into a new working model”. Why did they want to do this? Because they don’t "benefit from their charitable and cause driven work” because "under the current structure and financing arrangements, they are prohibited from earning any income in any form”. The Sussexes however "value the ability to earn a professional income, which in the current structure they are prohibited from doing”. And so this is why they have chosen a new approach - it will "enable them to continue to carry out their duties for Her Majesty The Queen, while having the future financial autonomy to work externally”.
They also intended to proudly maximise the Queen’s legacy "by supporting their patronages and carrying out works for The Monarchy within the UK or abroad, as called upon".
Their plan, clearly set out in their own words, was give up receive "funding through the Sovereign Grant, thereby making them members of the Royal Family with financial independence” (the Sovereign Grant provided 5% of their funding needs, the other 95% coming from then-Prince Charles). Their intention therefore was to still be bankrolled by Prince Charles, but no longer be subject to the Nolan rules, which prohibit them from benefitting financially from their position. This, they described, would "carve out a progressive new role within this institution” while they "continue to collaborate with Her Majesty The Queen, The Prince of Wales, The Duke of Cambridge, and all relevant parties”.
They couldn’t have been clearer: they wanted to stay royal but make money based on their royal status. Once the Royal family made it very clear that this was not actual possible, and they had to choose to either be wholly in (and bound by the rules) or wholly out (and free from them), they went for the latter, as they obviously wanted the ability to earn money. Prince Harry made their position perfectly clear at his January 2020 speech at a Sentabale event: "Our hope was to continue serving the Queen, the Commonwealth, and my military associations, but without public funding. Unfortunately, that wasn’t possible”.
No speculation at all, you see. If you say otherwise you are the one ignoring what they clearly told us.