I think the best option is to save in Lightning, but ignore the option of storing within the exchange.

You can accumulate your Lightning SATS in a self-custody wallet, and when you have more than 100,000 SATS, you can start building your UTXOs on the main chain.

bitcoin_beginners

How to reduce the fee link to a weekly purchase of 5k Sats?

kakashinaruto

This comment is spot on. 

I think the best option is to save in Lightning, but ignore the option of storing within the exchange. 

You can accumulate your Lightning SATS in a self-custody wallet, and when you have more than 100,000 SATS, you can start building your UTXOs on the main chain.