Long story short:
I'm a senior full stack web developer and a few weeks ago I lead a workshop on Progressive Web Apps. For this workshop I had to do a lot of setup on a Linux box - FTP accounts, web server, SSL, etc. ... and I really liked it. I've done such things before, but this time all was successful from-the-first-time

... and I really enjoyed the final result

...
So I decided to check if such work is for me and therefore I researched a little bit - the knowledge, the certifications (LFCE and RHCE) ... but unfortunately I saw it's less paid than my current job. At least in general.
During the research, however, I met articles and forum topics on pen testing ... I liked the topic and now I'm really considering beginning to dig into this.
Can you help me with some opinions on this, taking the following into consideration:
PROS:
- Experience as web developer will be helpful there.
- Even if I don't end up doing it - the experience in pen testing will help me be a better developer.
- Currently I'm using mostly Linux environments - at work and at home - so I already have some (minimal) knowledge to start with.
- The salary will be comparable to the one I currently get, and with a mortgage this is important

- The topic is interesting and so far I like the stuff

CONS:
- In a few months I'll get 35 years old
... and spending a few years from now on to dig into a new area ... looks a little bit like I'm "too late and too old for the party".
- I already see that it's hard for me to memorize some stuff
... for example - a lot of Linux commands. I'm confusing a lot of them (find vs grep let say: find requires path at the beginning while grep - at the end) - and I can not memorize that well. That's why I'm referring to the "man" for the specific commands, and I'm doing this a lot.
- Eventually I will have to start over my career, while I already have something solid (~10 years experience so far). This makes me feel like I'm risking a lot.
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However I already started watching videos and reading articles, mostly to "see" whether this IS for me or not.
To summarize: any advises are welcome

Regards,
P.