Taking the first option listed above, which is to buy the underlying, you become the direct holder of the digital asset. Upon purchase, the cryptocurrency is sent to your bitcoin address or account (wallet) with the exchange. From there, you can transfer the crypotocurrency to any bitcoin address or wallet address using your private key that verifies you control ownership of the asset.
Verification Requirements – The vast majority of the Bitcoin trading platforms both in the US and the UK require some sort of ID verification in order to make deposits & withdrawals. Some exchanges will allow you to remain anonymous. Although verification, which can take up to a few days, might seem like a pain, it protects the exchange against all kinds of scams and money laundering.

Accept that coins can go to zero, and even good coins can lose up to 80% of their value (especially against BTC). There are many coins that didn’t make it to 2018 that were once highly valued and popular. Meanwhile, even some giants of today like ETH and XRP have seen their value in BTC prices drop to depressing levels. You should prepare for this mentally and have a strategy that factors this in. If you buy the dip in ETH from .15 down, .08 may look like an excellent price, but you have to be ready for .02. ETH holders who didn’t prepare for this had a depressing June 2017 – December 2017. Heed my warning, that new coin doesn’t have to moon twice, it can go to literal zero, and even those that will moon again… they can have long seasons of stagnation in between (where they lose value against BTC for months on end). See the Crypto Graveyard and please look at the historic charts of major alts like XRP (the gap between moons is real and some coins really don’t make it).
No, the successful trader is not me. I’ve gotten lucky a few times and I’m still refining and trying out strategies; on the other hand, I’m part of communities of people who trade on a daily basis to grow their portfolios, and while some of the results can be attributed to luck, a majority of it is based on fundamentals, good habits, and experience.