Everyone from the player base should have the same opportunities and be treated equally, regardless of the "thousands of dollars" they spend in the game. As a player, you can choose to pay money to progress faster and unlock the game's content more quickly because perhaps you enjoy the game and, by doing so, you also fund the development of a great game.
However, that is not the point you've made. You are discussing unlocking new content that isn't available unless you spend money, and that is a very dangerous mindset to adopt. If not all players are treated equally, then you, as a company (Plarium), will be creating a divide between the players who spend money—the "valuable" ones—and the "disposable" ones.
If one cannot afford to pay or simply chooses not to, they should not be treated as less important. Such an attitude towards non-paying players will likely drive them away from the game over time. Project this trend into the future, and the game will gradually lose all the players who don’t spend money, including those who once did but have ceased to do so. Eventually, only those who continue to pay will remain.
This is a dangerous scenario for a company, becasue your goal should be to expand your audience. Creating this virtual barrier -a "pay to unlock" model -will make the game more frustrating, more unequal, and less appealing for new players who are unfamiliar with it.