There is no doubt that Google and Facebook have become massive monopolies in the tech industry. It seems nearly impossible for anyone to compete with them at this point. However, that does not mean that it is impossible to defeat them. There are a few ways that this could be done:
1) By creating a better product - This seems like the most obvious way to defeat a monopoly. If you can create a product that is better than what the monopoly is offering, then people will naturally start using your product instead. This is easier said than done, of course, but it is definitely possible.
2) By offering something unique - Another way to compete with a monopoly is to offer something that they don't. This could be a unique feature that your product has, or a different business model that gives people a reason to switch to your product.
3) By government intervention - In some cases, the government may step in to help level the playing field. This could be in the form of regulations that make it harder for the monopoly to operate, or by breaking up the company into smaller pieces.
4) By change in consumer behavior - Finally, it is worth noting that monopolies can only exist if people continue to use their products. If enough people decide to switch to a different product, then the monopoly will be defeated.
Of course, these are just a few ideas and it is by no means an exhaustive list. Defeating a monopoly is a difficult task, but it is not impossible.