When Bitcoin hardfork to Bitcoin Cash and then hardfork to BSV, what will happen to Bitcoin and why does this cycle of hardforking keep continuing?

To put it into layman's perspective, a hardfork is like a disagreement between 2 parties.

Perhaps, Person A cheated on Person B.

Perhaps, Person A disagreed with something that Person B have said

Perhaps, Person A has a defect that Person B has to avoid at all cost.

OR

Perhaps that Person A thinks that he/she could Outdo Person B

Because of that, Bitcoin has gone through several hardforks. Bitcoin Cash and Bitcoin Satoshi Vision is a result of disagreements within the Bitcoin community over how it should proceed in the future.

While we are certainly not a Bitcoin Maximalist nor Hater, we will certain that more hardforks will happen to not just Bitcoins, but other Blockchains as well in the future as the space matures.

That's right, matures ;)​​​

This has no effect on Bitcoin, apart from the fact that the mining power is slightly split. Hardforks usually happen for political and economic reasons. As a beginner, you should definitely stay with Bitcoin (BTC) until you are more familiar with the topic. The forked coins usually have a different idea of how Bitcoin should be designed, which doesn't necessarily mean that they offer progress (usually the opposite).